Chiaki is a lazy girl who attends the same lectures as Haruki at university but, although she tends to cling to Haruki, it is later revealed that she does it to gain experience for her acting career. As the guy who broke the hearts of the school’s most beautiful girls, Chiaki thinks she can extract a lot of important information from him, though she would also fall in love with him later on.
Chiaki also talks to Setsuna to get more details about the whole situation. After getting drunk, Setsuna confesses about what happened to her and, although she doesn’t reveal any names, it’s clear to Chiaki she’s talking about Haruki. Setsuna states that she would like him to be equally nice to everyone but herself, who should remain special to him.  She loved everything about him, including even the way he looked at her so affectionately.  At this point, Chiaki notices she’s just included a third person in her story,  but Setsuna doesn’t pay attention to her and continues regardless. She tells of her love for the small details about him,  but also says it may have been better to let him go and be a part of their world, then he would still have held some fondness for her.  This would have been preferable if he was not going to be with her anyway, it would have been preferable to seeing him crushed with regret.  It was, she revealed, all her fault. After all, Setsuna confesses, she knew all that was going on, and she still fell in love with him regardless.  Apparently, Chiaki understands her situation,  and by the end of the conversation, Setsuna is shocked that she had revealed so much. 
 Even if he might be a little annoying, and even if he might complain about stuff all the time, he’d never abandon me, no matter what.
 He’d be equally nice to everyone else, but save a special sweeter side just for me. Wouldn’t that just be the best?
 You know, I… I loved him when he would look over to her with those gentle, affectionate eyes.
 Those little details of him seemed so lovely… That’s how I felt.
 If he still held some fondness for me, nevertheless… If I could just have been with them in their own world.
 Compared to seeing him crushed with regret, broken down into so many pieces…
 After all… I knew what was going on from the beginning, and I still fell in love with him regardless.
 I see… You’re a woman too, after all.
 I can’t believe it… Why is it? How did I end up just wanting to tell you everything?
In Chiaki’s route, Haruki goes to see her following the hotel incident with Setsuna. After he hugs her, she comforts him and then they kiss. Haruki soon takes her to his apartment, where they stay cooped up together for a week having sex:  a sin that he considers to be so sweet yet unfair because Setsuna is still in the grip of her emotional darkness.  Chiaki has two main objectives for staying with Haruki: first, she wants to gain experience for her acting career. Also, just like Koharu, she wants him to be happy and move forward … even if it’s not with her. Despite Chiaki asking Haruki several times whether he would like her to stay with him or not, he doesn’t show any determination for their being together and tells Chiaki to suit herself.
 I won’t reject no matter what’s done to me… if it’s you, Haruki.
 Only I was able to break out from the darkness. Once again, I committed a new sin.
 … A sin that’s this sweet but also so unfair.
He also reveals to her that he’s worried because time didn’t heal anything over the past three years  and that is why he couldn’t forgive himself and get closer to Setsuna. However, Chiaki’s explanation for this is that he had no rest during that time.  Normally, she tells him, when someone gets a cold they need to rest and take their medicine,  so that’s what she believes he should do now.  When Haruki inquires as to what she means by ‘medicine,’ Chiaki answers by kissing him.  She also explains that it’s important he doesn’t do anything during the recovery process, including cooking, washing or cleaning, and she would get angry if he tried to do anything. 
 Because time did not solve anything for us in these past three years.
 That’s because… Haruki didn’t rest.
 Normally when you catch a cold, you would get plenty of sleep, not do anything, take your medicine…and stay put until your body heals, right?
 So for now, you should get plenty of sleep, not do anything, take your medicine….
 What medicine…!? Nnn, nn~!!
 Ahhh~ you’re trying to do work again~! Don’t think about useless things until you’re completely healed.
 But my strict doctor won’t even allow me that amount of labor.
As Haruki starts to heal, Chiaki also achieves one of her objectives and gets the experience she wanted for her career.  At one point, though, she wants to know more about his love affairs, and Haruki talks to her about Kazusa, who is described as his first love. He also talks about Setsuna, whom he also loves and wants to be forgiven by,  but he can’t get close to her because of what he did. After a week, Haruki states that he’s already recovered  and that it’s time to overcome his Chiaki dependency.  Then he repeats that he’ll be fine from now on and thanks her for everything she’s done:  It is because of her that he is back to being his usual self. Haruki still admits, however, that he’s not completely over Setsuna. 
To his surprise, Chiaki argues that it’s fine even if he depends on her forever,  and so Haruki offers her the possibility of starting an actual relationship together, but also states that he won’t cling on her any longer.  If she wants to leave, however, he won’t stop her.  For Chiaki, Haruki’s words are a bit painful as they indicate he can move on without her  and, in the end, decides to leave. But before they part ways, Haruki asks if she wants to have sex one last time. Chiaki accepts even though her monologue reveals that she no longer had anything to gain from Haruki – being with him was no more about the reason.  Once Chiaki is gone, Haruki wonders if the reason was not that she got ‘tired’ of it all, but that she actually put him before her own feelings. 
 He’s teaching me the joys of being a woman and a mother~ I seriously can’t get enough of him. I probably won’t even mind having his baby… oh wow, this is amazing, female lines are just flowing out of my mouth effortlessly.
 But still, I loved her. That’s why I wanted to believe that I would be forgiven after these three years.
 You mean… you’re fully recovered?
 It’s about time I overcome my Chiaki-dependency.
 Thanks for everything, Chiaki… but I think I’m okay now. I’ll be okay.
 I’m still not completely over Setsuna.
 … It’s finnee~ I don’t care if you depend on me forever.
 In other words, I’m not needed anymore?
 Then I won’t stop you. I hope to at least see you off at the station, but I won’t get mad even if you leave by yourself.
 It’s a bit painful to stay beside Haruki who’s able to function on his own.
 You’re really fine even without me now, Haruki. Have to say I’m a little hurt.
 [F16 “There’s no more point in doing this.][F16… But this is not about reason.]
 In the end, did she place me first before her own feelings?
In order to reach Chiaki’s ‘true ending,’ she must truly be important to him. If not, a short ending appears where he moves on without her. In this ending, during the week following Chiaki’s departure, Haruki checks out whether she goes to university or not, but he doesn’t phone her  because he’s too busy going back to being the old Haruki that everyone knows. He also tells Takeya and Io everything that happened  – which gets him a slap from Io for his misconduct – and soon afterward Setsuna sends him a message. When he looks, the message says that if he reads it and finds it ridiculous, he can put her on his blocked list considering how horrible she was with him at the hotel. But Setsuna continues by confessing that she always ends up thinking about him so, after much agony, she decided to send the message.  It also explains that, in spite of her feeling relieved if he is completely fine and has already moved on, she would admittedly feel disappointed. 
 I hadn’t phoned her once, and there weren’t any calls from her either.
 I told Takeya and Io everything about my winter break.
 But I somehow always end up thinking about you… So after much agony, I decided to send this mail.
 Or are you completely fine? Have you already moved onto a new life? I’ll be relieved if that’s the case, but also feel a little disappointed. Am I contradicting myself?
Not without reason, Haruki considers what happened was his fault, not Setsuna’s, and wants to know how she’s doing. She explains that, despite having cried for him until her tears were dry,  she’s now feeling better. Haruki, however, will soon decide to write her a letter that will bring her even more tears. After finishing it, he mentally thanks Chiaki because now he’s able to get back on his own feet by himself.  It is because of her that he can move forward without fear of what awaits,  and at the same time he can still remember the time spent with her.
 … For a while, I cried until all my tears dried up
 I’m already able to get back on my feet by myself.
 Thanks to the memories that Chiaki gave me, I am able to move forward even without her beside me.
 And that’s why I’m moving forward. Without fear of what awaits.
In his letter to Setsuna, Haruki explains everything about his most recent infidelity without leaving anything out. He says that he’ll understand if she feels there is nothing more to say between them, but wants her to know that he’ll keep waiting regardless. In her reply, Setsuna tries to stay positive.  For her, it feels very nostalgic because she gets to see his beautiful and well-ordered handwriting which, after he changed departments, she no longer had the chance to see.  Setsuna also thanks him for writing it in a way that’s easy to read and essay-like, which reminds her so much of him. Now… about the actual content of the letter…  she admits that it’s going to take her some time to digest the truth.  And even though she believes she’s to blame for what happened, she can’t stop herself from reading the letter countless times. She gets angry, laments and, ultimately, becomes the disgusting girl she hates to be once more.  Her final words are a request for him to please wait in his current state (Note: current state as in no more cheating while her heart comes to terms with what he had just done.)
 I think this is probably the first time Haruki-kun sent me a letter?
 Just like your class notes, your handwriting is beautiful and well-ordered like always. It really feels nostalgic.
 Ever since Haruki-kun changed to the Arts Faculty, I no longer have the chance to see your handwriting after all.
 Anyway… onto the important matter. About the content of the letter…
 But to tell you the truth, it’ll take me some time to digest this harsh truth…
 Although I read it over and over, again and again, I’m deeply troubled. I get angry, I lament, I reflect on myself…. I become a person I hate somewhere no eyes are watching.
Soon afterward, Takeya and Io invite both Haruki and Setsuna to go skiing. This is a good opportunity to reconcile and so Setsuna sends Haruki a message telling him that she won’t go unless he goes as well.  Haruki wants to make sure she means what she says. After all, he’s a cheater and, knowing the other two, in the end it’s gonna be just Setsuna and Haruki.  Setsuna, however, tells him that she already knows that and asks him if he doesn’t like to be alone with her. The ending concludes with Haruki quickly replying that he’ll go.
 Eh? Haruki-kun, you’re not going? Then, I won’t go either.
 You went on a ski trip last year, right? Takeya-kun told me. I was kinda looking forward to having you teach me.
 You realize it’ll just be the two of us…?
In Chiaki’s ‘true ending,’ she becomes the most important person for Haruki. His monologue, from one week after Chiaki’s departure,  is the same as the other ending, except that this time there are new sentences where he decides to take the initiative and meet her instead of letting time pass.  This is because he needs to know if she sees him as a friend or something else. Later, Takeya and Io pay him a visit and get to know that he’s been with another woman. To no one’s surprise, Io quickly goes berserk because, all the time Setsuna has been crying alone, he’s been ‘doing’ another girl.  The reason Haruki hadn’t been able to completely let go of Setsuna for so long is because of his selfish yearning to be with her.  But now, Haruki realizes, it ends there, and he asks Io to take care of Setsuna.  Io shouts, asking why he’s giving up on her, but Haruki says she doesn’t even need to ask. When Io later asks if he really cherishes Chiaki so much,  Haruki’s determined answer makes it impossible for Io to forgive him. A new feeling has been born in Haruki’s heart, a feeling to cherish Chiaki,  but Io can’t forgive his decision as it’s too unfair on Setsuna. 
 Waking up at six thirty, eating breakfast, resuming my part-time jobs, coming in contact with people other than Chiaki…
 Since that’s the case, I decided last night to take the initiative and go meet and talk to her.
 Were you in each other’s arms when Setsuna was crying alone?
 Doing the exact same thing you did three years ago! Just how many times do you have to go wrong before you’re satisfied!
 It’s because of this yearning for Setsuna inside of me… this disgusting opportunistic feeling of mine…
 Take care of… Setsuna. Even if you decide to never see me again, stay a good friend to her.
 … Do you treasure that woman that much?
 A feeling of yearning. Of wanting to cherish that woman.
 I can’t forgive him. It’s too unfair to Setsuna. There’s no way I can forgive him…
Later, after having been crying for 10 days non-stop, Setsuna sends Haruki a phone message.  Haruki, however, has already made up his mind not to accept her feelings for him, though realizes he might be stupid for having fallen so deeply in love with Chiaki.  He makes many phone calls and actively searches for her, but Takeya, who had sided with Haruki, finds her first, and quickly tells Haruki he’s not to believe a single word from that woman. It turns out that she was making a theater play out of his romantic life with Setsuna and Kazusa, and believed that spending a lot of time with him would make her a better actress for the play. After Haruki goes to see her, Chiaki tells him she’s been using him for her own sake, and he cries bitterly. 
Soon after, Io confronts Chiaki and asks what her feelings for him are. Despite saying that she loves him,  Chiaki also considers she did nothing wrong – what she did was protect Haruki so that he wouldn’t break.  And even though Io believes that her initial motivation is messed up, Chiaki insists that the fact remains that she saved Haruki.  In the end, time will solve everything and Haruki has to do nothing.  Haruki, however, has fallen too deeply in love with Chiaki, and despite knowing she is the wrong choice,  he still wants her anyway. His friends try to sway his decision toward Setsuna,  but love doesn’t follow common sense,  and he rejects their invitation to go skiing with her.
 I like him. I love him. I wouldn’t sleep (with him) if I didn’t.
 I comforted Haruki, who had been hurt by her, and I always protected him so that he would not fall apart… Yet I am the only one at fault?
 That doesn’t change the fact that I saved him.
 It will change. Even if Haruki doesn’t do anything, time can change something.
 That’s why… Without doing or thinking about anything right now, I will wait patiently for time to solve things.
 There is no girl as good as Setsuna-chan, and there is no woman as uncertain as Seno.
 From the perspective of correctness, what Takeya is saying is perfectly correct.
 Haruki, break off with her once and for all. After suffering so much, haven’t you learned your lesson?
 However, if people could decide everything based on correctness, nobody would ever have to worry like this.
Setsuna had previously gone to his apartment and tried to offer him her warmth, but he rejected it and instead decided to tell her about the time spent with Chiaki… and even about the possibility of him having chosen that woman. Setsuna had always wanted to be with Haruki,  she wanted to put his mind and body at ease  and melt all his suffering away. She felt he had been disheartened because of her, and so he could use her as he pleased.  She goes on to say that, because it was him, she would even become a substitute for any woman  as well as taking all his pain upon herself.  But she had failed miserably as he had not let her do anything for him for three years. Still, she wants him to know that she doesn’t hate him and that he doesn’t have to feel guilty because of his love for Chiaki.  Now, they can still be together even if it’s not as lovers, so everything will be all right.  After that, Setsuna tells him she’ll never betray him and will let him be in Chiaki’s care – though she still insists that they keep being together forever. 
 From now on, I’ll always warm you up…
 So that your mind or body is not in distress.
 After all, you were disheartened because of me. So you can make use of me without holding back.
 Being a substitute is OK, it’s all right. I’ll be a substitute for whoever it is.
 I’ll take in everything instead of you.
 I’ll… warm you up, OK?
 No matter what happens, I’ll never hate you.
 So you don’t have to hide it.You don’t have to feel guilty towards me…
 However, now we can also be together like this. Be it as lovers, as friends, as friends of friends, we’re always connected.
 That’s why it’s going to be fine going forward as well. That’s what I believe.
 However… From now on we’ll still always be together, right?
Later, she has a conversation with Chiaki. Setsuna had already realized that, despite Chiaki’s behavior, her love for him was genuine and that she was truly happy during her time with him.  Not only does she not hate Chiaki,  but also thanks her for having helped and saved Haruki, which in turn resulted in saving her as well.  Setsuna had promised herself that she would support him instead of Kazusa,  and yet, all she was able to do was force her own feelings on him and hurt him.  In the end, even if it’s with another woman, what Setsuna wishes is for Haruki to be protected. 
 At that time, you seemed to be so happy.
 But I’m sorry, I also cannot hate you.
 Thank you for helping him.
 Thank you for making him happy him instead of me.
 You see, I made a promise. That I’ll support him instead of Kazusa.
 And yet, what I did was rather the opposite. I forced my own feelings upon him, and I hurt him…
 Please protect Haruki-kun, please.
Sometime afterwards Chiaki performs a play based on Haruki, Kazusa, and Setsuna’s lives. In the end, Haruki decides to go see it, and he takes Setsuna with him. Because of everything that had happened, Haruki was starting to question whether or not he should be with Chiaki, so for a short while considers making up with Setsuna.  Maybe, he ponders, a bright future will open up for them, and the last three years will simply appear to have been a bad dream for Setsuna. In the play, Setsuna’s character is called Yukine, Kazusa is called Haruna and the Haruki character is Kazuki. When it finally begins, Chiaki uses all the information and emotions Setsuna and Haruki have revealed to her in order to transform herself into Kazusa and Setsuna. And although the play has a few discrepancies compared to the real story, it’s impossible for Haruki and Setsuna to pretend they’re not watching a play of their own lives (Note: a couple of elements that the play hinted at will actually appear in different parts of the White Album 2 world. For example, one of the side stories where Setsuna confronts Kazusa and tells her face-to-face that she loves Haruki and that she declares war on her for him.)
Yukine’s monologue at the end of the play, which takes place after Kazuki has cheated on her, is particularly packed with emotion. First she sings the song, ‘Todokonai Koi.’ After that she monologues as if talking to Kazuki, displaying her determination to have his love. She tells how she won’t throw her feelings for him away,  and that she’ll keep on fighting. If she does her best, then maybe, and before she even realizes it, she will get her chance. Kazuki, she grieves, may end up getting hurt,  but Yukine will not regret having tried, and she won’t give up. Feelings, she considers, have no limits on their strength or number,  and as her feelings for singing became stronger, her feelings for Kazuki certainly did not become weaker.  Yukine remembers her feelings for Kazuki when she couldn’t meet him, and those she felt when it was just the two of them.  She remembers them too well, and knows her feelings will not lose  and that she will risk losing everything to try and win.
Even so, no matter whether Haruki chooses Haruna or her, she will not condemn him.  Yukine’s feelings will not lose to those of Haruna, and neither will Haruna’s feelings for Kazuki lose to those of Yukine. Still, they must accept whatever Kazuki decides.  Yukine then thinks about how much she loves Kazuki,  ending both her monologue and the whole play.
 Hey, Kazuki-kun.
 I won’t throw it away.
 My feelings toward you, the chance I hold in my hand, my dreams…
 As a girl, my feelings of being in love.
 Perhaps if I do that, I’ll hurt Kazuki-kun without meaning to …
 Feelings have no limit on how many you can have or how strong they can be.
 As my feelings for singing became stronger, my feelings for Kazuki-kun didn’t become any weaker…
 My feelings grew when I couldn’t be with you, and the few times it was just the two of us made them grow even more.
 So my feelings will not lose at all.
 Whether you choose me or Haruna, I will not think it’s wrong.
 My feelings will not lose to Haruna, and given that the same goes for Haruna too, all that’s left is for Kazuki-Kun to decide.
 Hey, Kazuki-kun…
 I really, really love you!
Once the play is over, Chiaki suddenly asks Yoshida if anyone is waiting for her.  To his surprise,  she immediately runs outside even though it is snowing and she is lightly dressed.  The reason, Chiaki explains to him, is that she has to make sure of something.  When he asks what, Chiaki answers it is to see whether she has lost everything.  Once outside, and realizing Haruki is nowhere to be seen, she starts to cry bitterly.  If it had gone well, she would have been able to go back to Haruki, and she would have let him take her of her for life.  Yet he had abandoned her,  and it seemed she would lose him. 
 There wasn’t anybody waiting for me? After the end of the performance, that…
 Hey, where are you going?
 Y-you can’t go out dressed like that! Outside now it is…
 Just for a bit… Just… to make sure of something…
 Whether I’ve lost everything.
 Uuhhahhhh… Haa, huh, huh… huh…
 If it had gone well, I would have been able to go back to Haruki. I would have let him take care of me for life, and yet…
 As a result, I… I was deserted, no questions asked, wasn’t I?
 It’s your fault things turned out like this! And now I am going to lose even you!?
At that moment, however, Haruki suddenly appears, and asks why she is crying.  Chiaki replies it is because he has dumped her  – she let him do anything, and yet…  Haruki then tells her to go to his room,  but Chiaki still insists he has dumped her.  He had gone back to Setsuna,  she explains, and now he is standing in front of her despite them making her look like a fool.  What Haruki tells her, though, is exactly the opposite – he had dumped Setsuna and come back for Chiaki.  Like this, despite Setsuna having been happy to spend time with him that day,  it had all ended with him betraying her once more.  He had completely broken up with Setsuna and even told her that, despite being hurt by Chiaki, he wanted the time spent with her to go on forever.  Later, Haruki helps the still trembling Chiaki to stand, and she asks him to forgive her.  But it’s not that easy for Haruki to forgive.  So, Chiaki asks for something else… for him to just hold her tight. 
 Why are you crying?
 Because you dumped me, Haruki.
 I let you do anything, but you… You go on and throw away your responsibility as a man.
 Let’s go home.
 Of course, back to my room.
 But you dumped me.
 You dumped me and went back to Ogiso Setsuna.
 Why did you appear in front of me after all this? In spite of the fact that you two made a fool out of me.
 Actually, of all people… I dumped Setsuna and came back for you.
 Thank you for inviting me today. I am glad I could see Haruki’s face after such a long time.
 I have to betray Setsuna.
 Tear Setsuna to pieces.
 I wanted it to go on forever – that’s what I thought.
 Haruki, didn’t you tell me to stand on my own? If I did, you said you would forgive me everything.
 It’s not so simple to forgive.
 In that case… hold me tight.
Six months have already passed since Haruki and Chiaki started living together, and they’re now a happy couple – though Haruki’s attempts to reform her character seem to have been in vain.  Chiaki still dreams of fame,  yet Haruki doesn’t have such high expectations.  Besides, a man who takes care of her just because she’s famous would be worthless. Even so, he would like her to be more independent, but Chiaki believes, despite Haruki’s skepticism,  that it will take her just three years to become famous and make him rely on her instead.  She then reminds him of her good results in her last audition, and Haruki has no choice but to drop the subject.  After asking for a reward for those good results, they kiss each other.  Later, Chiaki tells him that she’s going to make him happy from the bottom of his heart.  He will no longer have to try so hard, suffer alone, or worry until he breaks down.  She’s going to completely paint him over. 
 The half year we’ve been living here together…
 I’m ashamed to admit I have not succeeded in reforming this person’s character.
 One day I’ll be famous and will give you an easy life, OK?
 I’m not some dreamy slowpoke to believe such hokum.
 I can’t trust such a wishy-washy dream. I’d rather you decide on a steady job, become self-supporting, so whatever happens you’d be able to live by yourself…
 Stop chasing dreams like that. Why not follow a more realistic path…
 You’re not listening, I’m saying you need to be patient for three years. If you do, this time I’ll make you rely on me.
 In her case, this talent is a problem, because it easily blows away my commonsense theories.
 So, a reward…
 I’m going to make you happy. Surely, one day I’ll make you say “I am glad to be with you” from the bottom of your heart.
 That’s why you don’t have to try so hard. You don’t have to suffer alone. You don’t have to worry until you break down.
 Give it some time, and I’ll paint you over, Haruki.