Himitsu no Houkago 2 ~Coach to Oshiego no Abunai Dousei Seikatsu~

Main character works as a teacher and supervises skating club. One female student gives a lot of promise, and he dreams of winning at Olympics with her.
One day unknown girl comes to his house and demands to keep promise and teach her playing fugue. Teacher does not recollect the promise, but lets her stay at the house.
At the same time president's daughter threatens to accuse him of harassment unless he spends a night with her. A one time thing escalates into longing passion, and soon two other girls start to demand equal attention.

[From vndbreview]