For as long as she could help it, Rias wanted to keep Issei away from her brother. Not Sirzechs though, but the other one. While he is kind, strong, and helpful, she just fears what Issei might become once they get to know each other...

Naruto Uzumaki was on his last legs against the Ten-Tails and in a last desperate attack that will lead to his death or victory, the collision opened up tears into reality and he got suck right into one! He expected to land in the lava world again but he didn't expect to land in a world full of cute girls who want to marry him through sex!