Maina ~Haja no Ketsumyaku~

Yoichiro comes from an old religious family, but he's unaware of his roots even though he has a potential. His parents worry about the decline of the clan and they decide to marry him on a talented spiritualist Mai even though he already has a fiance Yuko. The demon is aware of Yoichiro potential and he tempts Yoichiro through his classmate Taeko.

[From vndbreview]