Tsukasa Atsumi, an ordinary salaryman, finds his life turned upside down when a demon attack leads to his rescue by Shizuri Ideura, a genius kunoichi. However, Shizuri is also a lazy otaku NEET who prefers gaming over her ninja duties. Their cohabitation begins with a master-servant contract, blending action and comedy as Tsukasa navigates his new reality while Shizuri protects him from supernatural threats.