As a child, Shiki Tohno suffered a life-threatening injury and was subsequently sent away from the Tohno family. Years later, after the death of his father (the head of the household), his sister Akiha instructs him to move back home. However, Shiki has a big secret: he sees lines on objects due to his injury and must wear special glasses to correct his vision. Additionally, he struggles to remember events before his accident. Upon returning home, Shiki encounters Arcueid Brunstud, whom he accidentally decapitates during a moment of insanity. Much to his surprise, she appears alive and requests his service as a bodyguard. This event sets off a chain of events as Shiki attempts to uncover the mysteries of his past.
