Nawatsuna Kawarazaki, master of the remote Kawarazaki Manor, possesses white slicked-back shoulder-length hair, a beard, and pale, wrinkled skin. He typically wears robes, trousers, and slippers, often seen smoking cigars. His birthday is August 13.

He hosts a birthday celebration at his mountain mansion attended by family: niece Anna, her boyfriend Yuuma, and cousins Maki and Tomoki. During dinner, Nawatsuna emerges cross-dressed in a fancy gown with clownish makeup. His unsettling presence fuels an eerie atmosphere, igniting family tensions when Tomoki confronts him, calling him a "creep and a jerk" and accusing him of being unpleasant. Nawatsuna counters by asking if others share Tomoki's sentiments.

Nawatsuna orchestrates a scheme to permanently trap his family within the mansion. He enlists staff members Mika and Inagaki to maintain a facade of normalcy while secretly securing the estate to prevent escape. When his plans are prematurely exposed—such as intruders discovering his hidden torture chamber—he accelerates his timeline. His manipulation extends to sabotaging escape attempts, including deliberately arranging vehicle breakdowns.