ボクカノ3 ～男の娘を好きになる純愛トライアングル+1

Tadakatsu Fusamoto was lazy during all his campus life, and now struggling to find a job.
He is sent to his old school for the teaching practice, and find Minami and Narumi, his twin little brothers, who push him around using their cuteness!
Then one day, he met a school girl in the school gym at night. He immediately fell in love with her, not knowing her true identity...

[From dlsite]