Ane Ore Imouto: Kyoushi, Doukyuusei, Kouhai no Kankei

The protagonist Kousuke attends school while living with his 3 stepsisters.
The oldest sister is his homeroom teacher, the second sister is his classmate and the youngest sister attends the neighboring girls school.
Kousuke starts developing certain emotions towards the sisters...
Mixing in a childhood friend and a student council president an exciting school life is about to begin.

(Source: VNDB)