When her second son, Masao, falls ill with a cold, Ryoko Sumikawa is busy nursing him back to health. One day, her eldest son, Tatsuya, visits the house to check on Masao, who is slowly recovering. A mistake from years ago—Ryoko had actually been in a romantic relationship with Tatsuya. Once again, Tatsuya begins pursuing a physical relationship with her. By chance, Masao witnesses the scene and trembles in disbelief, falling ill once more. Realizing Masao's pure feelings, Ryoko becomes confused and unsure of what to do.