Eiji Urashima, a typical university student, leads a life of partying and pursuit of romance. However, his world turns upside down when he wakes up to find a beautiful classmate claiming to be his girlfriend, with no memory of how they got together. As bizarre events unfold, Eiji realizes he has lost three days of his life. The revelation of his dark family secret as the son of a serial killer further complicates matters. Determined to fix the chaos and earn Kyouka's acceptance, Eiji sets out on a quest to unravel the mysteries of the missing days.