Lunar Legend Tsukihime

Shiki Tohno sustained a life threatening injury as a child, and due to that incident he was sent away from the Tohno household and was given to a relative to be raised. Years later, when Shiki is in high school, the head of the Tohno household—his father—dies, and he is ordered to move back in by his sister Akiha, who is the new head of the household. However, Shiki holds a huge secret...