At the transition from late winter to early spring, when temperatures are unstable, Koichi catches a cold. He ends up infecting his wife, Natsumi, who is hospitalized for an extended period due to tonsillitis. During this time, his beautiful mother-in-law, Mirei, comes to visit and begins taking care of him, providing such comforting company that Koichi nearly forgets how sick he feels. Though his health improves, he becomes increasingly drawn to Mirei's tender attentions and deliberately calls in sick to work, prolonging his recovery. What unfolds next is an unexpected turn of events...