Yuuri, a married woman, is happily preparing for her daughter Risa's upcoming wedding to her boyfriend Akihiko. Wishing nothing but happiness for the young couple, Yuuri begins to notice something strange when she catches Akihiko holding her underwear after she steps out of the bath. His behavior changes, becoming noticeably different around her. One day, left alone together, Akihiko suddenly pleads, "Just once," and makes a move on her. What follows is a complex, shifting bond between mother and daughter's fiancé, unfolding amidst the quiet tension of daily life, capturing the subtle transformation of their emotions and the strange atmosphere that grows between them.