It's quite old, the story starts when a student went to the mc's office… i cant remember if the mc is a school teacher or school physician, but it's a school setting and he gave office there, now, the student went to have consultation, that's when the mc did her (i beleived that he quite hypnotize the student or something like burn some incense/candle to make her sleep or some sort… cant remember)… then after that the story goes on and he found out that her mom was once a student at that school… later on he found out that the student was his child since he was the one who impregnate her mother….