While testing his old camera at the magnificent night sky, Nathaniel Mendoza caught amid a mysterious explosion in his town. Surprisingly, he wakes up the next day totally fine, but with no reminiscence of what precisely happened the day before. However, during the time he encounters flashes from what happened and also vaguely remembers someone grabbing his hand and saved his life that night. The next day, a girl transfers into his class named Luna Swan, as she appears an exchange-student. Through coincidence, a bizarre twist that she ends up living with him while their personal relationship slowly blossoms.