Sister Ephnel, Falling into Darkness by Futanari Succubi

Bad Sister Ephnel is an adult visual novel/game featuring a nun protagonist who disobeys her vows and is captured by a group of futanari succubi demons. As she is repeatedly assaulted by the demons—including Dhana (a mischievous minor demon), Lily (a prideful aristocratic demon), Chii (a hedonistic cat-like demon), and Stella (the succubi leader)—Ephnel gradually succumbs to corruption and pleasure, ultimately embracing darkness. The game features multiple interactive scenes depicting various sexual acts, with branching story paths and different endings based on player choices.