Years after marrying her husband "Tetsu," wife "Yuko" still hasn't managed to grow closer to her stepson "Manabu." This summer, taking advantage of Tetsu's vacation, she returns to their hometown determined to build a better relationship with Manabu. However, the old wooden house without air conditioning proves far more oppressive than she imagined, unaccustomed as she is to rural life. The relentless heat bears down on her body, sweat pouring from her neck, cleavage, and underarms, gradually stirring something within Manabu. That lewd, glistening sweat begins shifting his perception of Yuko—not just as a mother figure, but as a woman—awakening emotions he can no longer ignore.