Koshiro is uncomfortable with Nanoka's doting presence as he struggles with his feelings for her. Nanoka takes over many of the households chores and even makes a bento for Koshiro. He reaches his limit when she arrives at his office to visit him, yelling at her, telling her to never visit him again and stop calling him Big Brother. To work off her anger Nanoka goes out with some friends to eat ice cream and karaoke until night. On her way back she calls once again, but is yelled at by Koshiro again. However she forgives him when he goes to pick her up on bicycle.

Nanoka discovers that she has developed a reputation at school for having a brother complex. After working late on the upcoming school festival, she is walked home by a male schoolmate. Koshiro encounters them and shouts at her for being so incautious with boys. She protests her innocence and his jealousy shows when he blurts out that she has to be careful because she is cute. Next day she avoids him by leaving early and gets jostled and groped on the train. They have a talk that evening and make up. Next day, he makes a point of going with her and protects her on the train from the crowd.