Risa and Atsushi are confused when a man comes running up to Risa to hug her. Introducing himself as Haruka Fukugawa, he insists he's a friend of Risa's from elementary school. At this, she recalls that he was frequently bullied for having a girly name, that she stood up for him, and that he had moved overseas. As the two reminisce, Atsushi finds himself left out and decides to go ahead without Risa.
On New Year's Day, during their trip to the shrine, Risa notices Mayu and pushes Atsushi toward her. She recognizes Risa and asks if she's Atsushi's girlfriend; the two vehemently deny this and Risa insists that because they aren't going out, Mayu can freely tell Atsushi what she wanted to say. Mayu apologizes to him, saying that she didn't break up with him because of his height and that she only realized he might have gotten that impression afterward. The two are taken by surprise by this, but Mayu leaves to go meet her boyfriend at the gate.
As Valentine's Day approaches, Nobuko and Chiharu discuss what kinds of chocolate to make for their boyfriends and Risa expresses her envy of the two. Nobuko suggests that Risa give some chocolate to Atsushi, to make up for misleading him about getting back together with Mayu. She barely has time to consider when Atsushi comes in with one of Umibouzu's CDs from his indie days and the two excitedly talk about it.
After school, Nobuko mentions to Heikichi that Risa will be helping her make chocolate, to which Atsushi expresses mock disgust. Risa takes the comment hard, however, and laments that she'll never have anyone to give chocolate to. Atsushi, somewhat taken aback by her serious reaction, says she could give some to him, since he likes sweets.
Later, while watching with Nobuko as Otani and Heikichi play basketball, Risa once again finds herself unexpectedly being hugged by Haruka. After he leaves, Atsushi asks why he came and Risa explains that he's going to be transferring to their school soon. At this, Atsushi sarcastically remarks that he's her type, which Risa denies, saying that he used to be a crybaby, look like a girl, and only had girls for friends.
Haruka is waiting for Risa as they leave the school and asks if she's free. She replies that she was going to go look for Umibouzu CDs with Atsushi, at which point Haruka notices him and is shocked at how short he is. Haruka claims that Risa is too cool to be seen with someone as short as Atsushi and the two boys antagonize each other for a while.
Finished making her chocolate cake for Valentine's Day, Risa is reluctant to give it to Atsushi because it's shaped like a heart. She decides to go through with it anyway, but is turned down by Atsushi. He says he only wanted to accept her chocolate because she had no one else to give it to, but now she has Haruka. Frustrated by his continued refusal, she leaves and ends up sitting alone in a park. Haruka finds her, saying he hoped she was going to give him some chocolate, to which she offers him the chocolate she was going to give to Atsushi.
The two then head to an arcade, where Risa relieves some stress. Afterward, Haruka asks Risa what her relationship with Atsushi is. Risa replies that they're just in the same class and walk home the same way. When he criticizes Atsushi, however, she defends him, thinking about how hard he tries at basketball practice, how he kept his promise to go to the Umibouzu concert with her, and how concerned he was about her on Christmas. Haruka remarks that she must like Atsushi, but that he's confident he won't lose to him.
The next day, Atsushi is glum and unenergetic. After Risa sits down, he apologizes to her. She briefly feigns a lack of forgiveness, but says it's OK, because it was only obligatory chocolate. The two share a laugh and the scene changes to Haruka dejectedly staring at a heart-shaped chocolate cake with a large "Obligatory" written in frosting.