Yukito, being the ambitious fucker he is, applies to be a domestic servant at a mansion. The landlady tells him he can only get the job if he masturbates in front of her. He gets the job.
The protagonist is in his thirties and is a teacher at a girl's school. He only wishes to train his students well and help them graduate. That is, until a student of his starts showing signs of interest in something other than her studies.