Hasebe Yuma

A very serious and polite athlete.
A member of the volleyball club who is active with her hard work, enthusiasm, and tremendous jumping power.
She's seen as a bundle of energy, but in reality, she's depressed due to being abandoned by her parents.
As a result, the protagonist finds out her weakness, and disciplined her.
Yume is an excellent pawn who will do anything the protagonist tells her too, and works hard not to be abandoned.