The Blackmail II: The Animation

Original: 脅迫Ⅱ[セカンド] ～もうひとつの明日～ THE ANIMATION

Asuka and Ryosuke decide to get married. However, Asuka gets abducted by a group of men right after the wedding, gang-raped and thrown into a world of sexual slavery. It got worse when Asuka's mother and little sister were also thrown into this horrible world with her. (Source: Anime News Network)