Murakami Nijiro (Destruction Babies) stars as Toru, an aimless college student who comes upon the aftermath of a murder scene one night, and without thinking, grabs the titular weapon. He takes it home and keeps it safely hidden away, but curiosity gradually begins to consume him. His budding relationship with a sunny fellow student suffers as his obsession grows, and he becomes reclusive. Then one day, a detective (Lily Franky, Shoplifters) turns up at his apartment and a dangerous cat-and-mouse game begins. Take Masaharu (100 Yen Love) adapts a prizewinning novel for this noir-tinged tale, shot mostly in luminous black-and-white.