For You I Will Kill Everyone: Project Dia Horizon manga summary: University student Shinji, who felt trapped in life because he couldnt make progress romantically or with finding a job, was given a chance to reincarnate. Moreover, he was given a "fated partner" to be with. He wondered if a happy life would begin, but then it began -- an eternal death game where he must kill constantly, only ending when he finally is killed him self.

"Dont worry, Big Sis will kill you."

Joining the murder spree with "Sister" Hilde, who shows an unusual affection towards him... The death game begins with a bond forged in blood!