Tokiwa, who researches cytology, one day discovers a new aphrodisiac substance. He thinks by using this substance he can make Kazuno, an impertinent college kid who makes fun of Tokiwa's research, want to be made love to; however, it doesn't go as planned after a large number of lab guinea pigs escape from the cage all of a sudden...Getting bit by a guinea pig makes Tokiwa's body rut with a huge boner. On the contrary to his feeling, his body wants Kazuno's body, "How did I become a bottom?" What is the outcome of this experimentation?