2D-kun calls Banri and tells him that he heard Banri was lonely. He offers to hang out, but Banri already has plans with Kōko. As they discuss their wish to hang out with Mitsuo (who has been too busy lately), Kōko arrives and overhears the conversation. She is suspicious until Banri hands over the phone and she discovers it is 2D-kun to whom Banri is speaking. Finding out that Mitsuo may have a girlfriend, she formulates a plan to determine her identity and enlists Banri’s and 2D-kun’s help. They start by watching Oka-chan’s house, thinking that she is the most likely candidate. Oka-chan discovers them, though, so Banri tells her they were just visiting her. To their surprise she tells them she’s free to hang out, and when asked she admits that she’s not seeing anyone and that she hasn’t seen Mitsuo since summer vacation started. Oka-chan invites them in, where they observe that the house is empty except for Oka-chan’s room. She explains that her family has moved away and that she will live alone while she finishes college. Kōko admits that she’s jealous of Oka-chan. Oka-chan replies that she is worried about living on her own for the first time. They reaffirm their decision to go to the beach together. They all go to the place the Film Club hangs out, but before they get there they observe Mitsuo and Linda walk in together as if on a date. To allow Mitsuo and Linda some privacy they decide to go somewhere else. Later Kōko arrives at Oka-chan’s house with a bag full of swimsuits. The two of them try the swimsuits on, and discuss Kōko’s and Banri’s relationship, and Kōko tells about Banri resisting her kiss in the park. She admits that she never feels they are “in the mood” when she and Banri are alone in his apartment. Oka-chan points out that Banri probably resists because he wants to show Kōko how much he really cares for her. Kōko tells Oka-chan that she wishes she could spend more time with Banri at his apartment. She admits that she questions whether Banri really loves her and is afraid he will disappear someday. She wonders if Banri is trying to find himself and if he does so if will he leave her. Kōko then states that the next two swimsuits she pulls out of her bag will be what she and Oka-chan will wear to the beach. They turn out to be school swimsuits. Oka-chan likes the idea and films them while wearing the swimsuits. Later in Banri’s apartment, Mitsuo and Banri discuss their swimwear choices as well. Mitsuo wishes he could have invited Linda and wonders where her hometown is located. Banri lies and says he doesn’t know.

(Source: Wikipedia)