Yusei and Kitayama were classmates and best friends. They weren't particularly outstanding students, but they had a secret. They conspired with Kita, a chemistry teacher, to repeatedly commit the extremely despicable act of giving aphrodisiacs to female teachers and students and seducing them into sexual acts. At first, he was just playing around and offering up his female friends, but soon Kita became overbearing, even going so far as to say, "You won't get credits unless you regularly offer me women!" And finally, his poisonous fangs were directed at Yusei's stepmother, Megumi...