Fed up with the monotony of everyday life, Mahiro one day encounters a pervert on the train. A man who had been harboring lewd fantasies about Mahiro happened to witness the incident and his lustful urges began to unravel. Then, on a hot day, the two found themselves on the same train again. Losing his reason to the smell of sweat under his armpits, the man starts to molest Mahiro, but the matter doesn't end there...
