Twin brothers， Taichi and Yosuke， are both in love with Tajima， a senior student at their lab. Taichi thinks that Yosuke is his lover. One day their study on germs creates an accident! They switch bodies! At first they panic， but then Taichi decides to have sex with Tajima. Right when things are getting good， something strange happens...!! It’s a story of losing your ”back virginity” by test tube， and erotic threesomes... It’s an ultimate must-read erotic story!