The story begins with a young man named Yuu, who feels stifled by life in his hometown. Seizing the opportunity to move to Tokyo, he moves into a cheap share house called “Hakobune”. Living in the “Ark” are a bunch of eccentric characters: Yamaguchi, who has a rough, gangster-like demeanor; Maru, who always wears a self-deprecating smile; Yoshiko, the oddly cheerful manager; Goro, who constantly makes provocative remarks; and Kirishima, who speaks politely but remains an enigmatic presence.Additionally, on the night Yuu moved in, Yamaguchi, who had been arguing with Maru, goes missing the next morning. Soon, Yuu starts to suspect that the tenants might be killing new residents based on their eerie behavior and conversations.