Oni basically acts like the big brother of the camp. He's genuinely skilled enough to be a 1st Stringer, but he deliberately stays on the 5th Court because he wants to push everyone else up—raising the overall level of all the courts.
During the U-17 camp, Oni plays on the 5th Court, where he's in a similar situation to Irie Kanata on the 3rd Court: both are clearly stronger than their court placement suggests. The 1st Court members openly acknowledge how powerful Oni and Irie are, even from their lower positions. When shuffle matches happened, the 5th Court ended up beating the 3rd Court—partly because Irie faked an arm injury and sat out—which bumped Oni up to the 3rd Court.
Content compiled by AnimeList.moe from publicly available sources.
