While his wife is away on a two-day trip with a friend, Akira settles in to enjoy having the house to himself. Then her older sister Reira suddenly drops by. Things have been going badly with her husband, and she secretly plans to satisfy her pent-up sex drive with Akira. Oblivious to her intentions, he relaxes after eating her home-cooked meal and heads for a bath—only for Reira to climb in with him...