Not only was he was twice as old as his student, the 31-year-old was also engaged to be married.
Still, the school teacher tried to get intimate with the 15-year-old girl.
And in her case, it turned into a situation of "heads he wins, tails she loses".
As their relationship became increasingly personal, he asked her if she would have sex with him as a forfeit if she lost a bet to him.
He also asked her to send him nude pictures of herself and she complied.
Later, when she was hesitant to join him in his bed, he gave her a coin and told her to flip it to decide whether they should remain platonic friends or start a physical relationship.
About a month later, the teacher had sex with the underage girl for the first time.
Yesterday, the man, who is now jobless, pleaded guilty in the State Court to five charges - four of having sex with a minor and one of performing an obscene act with a young person.
Another five charges will be taken into consideration when he is sentenced on June 30.
The man, a former scholar and Head of Department in the school, cannot be named to protect his victim's identity.
Court documents revealed that he had sex with the minor on various occasions between September 2012 and May last year, always unprotected, except once in November 2012.
His crimes were discovered only after the girl was admitted to hospital with suicidal tendencies. (See report on facing page.)
They became close after an overseas school trip in June 2012, and she started confiding in him about her family and her difficulties with her studies.
The same month, he got engaged and told his victim about it.
During the September school holidays, he invited her to his parents' flat - where he used to live - when they were out.