Minami, a beautiful mother, lives alone with her son. With her husband away on a long-term overseas assignment, she has been feeling profoundly lonely. One day, her son's best friend, Koichi, visits to cheer on a Japanese track athlete as they attempt a world record. Koichi, who has harbored feelings for Minami since childhood, suddenly steals a kiss. Despite her internal resistance, Minami feels her heart racing uncontrollably. As Koichi continues his advances and steals another kiss, the unfaithful desires she had kept suppressed finally catch fire...