In line with the erotic game by Guilty eX. Two sisters, living peacefully using grandfather who heads a Yakuza group, face a dilemma when their grandfather falls ill and the other rival group starts putting pressure. Sizzling hot out is usually to accept the deal with another Yakuza group for support in return for one of the girls.

Kuga Masaya receives a letter from which he learns about his father's death, which lately is not communicated. Also that he has a half younger sister. To learn more, he arrives at an island where lived a father and sister living...