2D-kun calls Banri and tells him that he heard Banri was lonely. He offers to hang out, but Banri already has plans with Koko. As they discuss their wish to hang out with Mitsuo (who has been too busy lately), Koko 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...