High School DxD Novel Vol. 2 (novel)

"RIAS GREMORY'S VIRGINITY BELONGS TO ME!"
Issei is finally beginning to adapt to his new life as one of the beautiful Rias's demonic servants. Just as things start looking up for the perverted high schooler, however, a cocky pretty boy named Riser arrives, claiming to be Rias's fiancé! To save the prez from a marriage she doesn't want, Issei and the other members of the Gremory Familia will have to battle Riser's team. Even with the mighty Boosted Gear at his disposal, can Issei really win against a guy who's said to be immortal?