Reincarnated As My Little Sister

Reincarnated As My Little Sister summary:

He, Yuuyami Riku, suffered from familial abuse. No, it was not from his parents. He was on the receiving end of his little sister’s violent tendencies. One day, he stood up against such a sister. For the first time, he told her off. And yet, on that night, his enraged sister stabbed him to death as he was fast asleep. However, Riku was reborn, and now was a baby. Jubilous about his new life, he almost didn’t notice a huge problem…