Sweet Punishment: I'm the Guard's Personal Pet(2018)

Overview

The story is set in a prison in the near future. It revolves around Hina Saotome, imprisoned despite her innocence, and the elegant yet sadistic guard Aki Myoujin. Hina's heart and body are at the mercy of Myoujin's "heartless yet sweet domination" from physical examinations to lovers' prison visits.