Isurugi Jun

Japanese name:	石動 純
Nickname:	Fourth

Jun is Noe's older brother. He is the captain of the basketball team at his school and is number four in his team. He is shown to have more feelings for Noe than just a normal sibling's relationship. He asks Shin'ichirō to ask Noe out, but Shin'ichirō merely gets annoyed at him. However, when Shin'ichirō requests that Jun go out with Hiromi in return for going out with his sister Noe, he agrees immediately. He does not hold any feelings for Hiromi, and is merely acting to make Noe happy.

Wikipedia