Recently, My Sister Is Unusual

Synopsis

Mitsuki Kanzaki is a high school girl whose mother remarries, giving her a new step-brother, Yuuya. Mitsuki struggles to bond with him, but things get weird when she is possessed by the ghost of a girl named Hiyori. Hiyori must pass on to heaven, but to do so, she must accumulate "happiness" through romantic interactions between Mitsuki and Yuuya. To ensure Mitsuki cooperates, Hiyori forces her to wear a supernatural "TSD" (a magical chastity belt) that only unlocks when she performs specific romantic tasks with her step-brother.