HAPPY!

One day the Yakuza comes knocking on the door of the orphaned Umino siblings. The oldest brother has gone into hiding after acquiring a huge debt. Afraid for her brother, Miyuki agrees to take responsibility for the loan. The yakuza wants her to become a ho, Miyuki wants to be a tennis pro. Turns out she used to be a very promising player before her parents died. However, becoming a pro is difficult when friends are few and everybody else conspires to make Miyuki's life hell. (Source: Anime News Network) — Description from AniList community (anilist.co).