Oni, Juujirou

鬼十次郎

He behaves like the camp's older brother. Although he is truly a 1st Stringer, he stays on the 5th Court because he wants to raise the level of all the other courts.
Oni appears in the U-17 camp on the 5th Court, sharing with Irie Kanata the fact that they are in lower courts than their actual skill level warrants. Despite being on the 5th Court, members of the 1st Court comment on how powerful he and Irie are, the latter being on the 3rd Court. Later, during the shuffle matches in the U-17 camp, the 5th Court defeats the 3rd Court because Irie pretends his arm hurts and cannot play, meaning the 5th Court replaces the 3rd Court and making Oni a member of the 3rd Court.