After discovering her husband's infidelity, Ayame temporarily moves in with her sister's family. Reunited after a long time, she unexpectedly stirs feelings in her nephew, Kounari. One day, Ayame catches him masturbating with her underwear. Overpowered by his aggressive demeanor, she gives in and surrenders her body. Feeling the vigorous young cock for the first time in a while, Ayame experiences a new thrill. Later, left alone with her sister's husband, Ayame finds herself caught in a whirlwind of new emotions.