Every time it rains, Aika's heart trembles. Her school uniform clings and becomes transparent, her underwear soaked—her appearance drives men wild with desire. The perverted janitor's favorite prey: drenched, big-titted schoolgirls. On a stormy night, when Aika is stranded and unable to return home, the man sneaks in through the rainy darkness. Each touch of her wet body flips his switch, turning him on. Night after night, as the rain falls, she continues to be raped. "My cock... it aches whenever it rains..." he murmurs, and gradually, Aika finds herself waiting for the rain too. After school in heavy downpour, once again, she resolves to head toward being violated.