Natsume Tomoharu, an ordinary high school student, carries a unique burden – the lingering spirit of his late friend, Misao. Upon settling into his brother's former residence, Tomoharu's routine existence takes a dramatic turn when he stumbles upon a cryptic, securely locked briefcase. Initially tempted to stow it away, he finds himself ensnared in a web of mystery and danger as various factions converge upon his home, all coveting the enigmatic case. Ignorant of its significance, Tomoharu and Misao embark on a perilous journey to safeguard the briefcase. As they delve deeper, Tomoharu unravels the intricate ties between the case, Misao's spectral presence, and its potential to reshape reality, propelling him into a quest for truth and understanding.