Misumi Kei, Rin`s elder sister, has just moved into the apartment next to Hayato`s. Rin is helping her adjust to her new neighbourhood and is going to be living there for the next few days. They have to keep Ui`s presence in his home a secret, so she has to hide every time Rin comes by to borrow some household items she needs. Distracted by Rin, he burns the fish he is cooking for dinner, and she enters his home uninvited. She discovers Ui`s panties lying on the floor, which he tries to explain away as being an aunt`s who recently visited. He tackles Ui into the toilet, where they hide while Rin uses the bathroom sink, and they rub against each other. Rin discovers Ui`s lip balm at the sink, which Hayato again tries to explain as his aunt`s, but this time Rin doesn`t believe him. He then says that the panties and the lip balm are his.