At her father-in-law's sudden request, Koh Shinana finds herself hesitating but ultimately agrees to help him relax by washing his back. The normally gentle and kind father-in-law now makes such a bold request, leaving her confused yet unable to refuse. Inside the bathroom, she is gradually cornered, and the moment his hands touch her back, she finds herself unable to resist strongly. The familial bond between daughter-in-law and father-in-law begins to twist into something unnatural under the touch of the man who once smiled at her so kindly.