Based on the erotic doujin game by Dekisui-sen Lilyon (溺水船リリオン).

Yuki Sakurano is on a winning streak as an illegal fighter in underground arenas. One day, the legendary fighter named King comes into her life to scout her as a fighter. Little did Yuki know that this event would drastically change her life in very different ways than she was expecting.

(Source: Steam)