Miwa's father believes that they are there for a tour. After learning that Yuu and Satoshi believe that he is Yuu's father, he explains to them that it is impossible. He never had an affair with Chiyako, not that he didn't want to. Satoshi tells his father about finding his mother's diary. She believed that he was having an affair with Chiyako. Satoshi's father explains that it was a great coverup for his other affairs. All the kids are embarrassed. He then asks Yuu what made him believe that he was his father. Yuu tells him about his Grandmother's letter regarding an old boyfriend and raising someone else's baby.
Yuu storms out at him, surprising everyone. He then settles down and gets very depressed. Satoshi wonders why his mom doesn't just divorce his dad.
They leave and Yuu asks Satoshi to take Miki home. Yuu walks away toward the beach. Miki tells Satoshi that she must follow Yuu and he says goodbye to her. Yuu sits by the ocean for a long time. Miki finally goes and joins him. She tells him that it is time to go home. He wants to stay just a little while longer. Then Yuu asks Miki to warm him up (it is getting cold out). He hugs her and starts crying on her shoulder.
They stay that way until sunset. He tells her how upset he was when he learned that Youji wasn't his biological father. Then, after sulking for a month, he realized how grateful he was for him mother for giving birth to him and to Youji for being his father in every way that counted. He says that since then, he hasn't believed in anyone. He is afraid of being betrayed. Yuu didn't think that he cared about anything. Then he wonders where his real father is.
Miki tells him that it doesn't matter. He has a family who loves him. He says he was so unemotional about the partner swap but Miki, unlike him, "is honest and pure". She has no problem expressing her feelings. She says, "You mean, I'm uncomplicated". He replies, "That's why...I love you". She tells him she loves him too. He calls her an idiot and says that she is just caught up in the moment. He says that in the same situation, she would say that to Ginta too. She convinces him that she truly does love him.
They kiss.