Shingetsutan Tsukihime

Shiki Tohno was removed from his family after a severe childhood injury and raised by a relative. He returns to live with his sister Akiha after their father's death. Since his accident, he experiences strange visual distortions and memory loss. On his first day back, he impulsively kills a woman named Arcueid Brunstud with a knife. Later, she reappears unharmed and asks him to serve as her bodyguard, prompting him to seek answers about his past.