NOVEL NEXT 
After the fight with Naruto in the Valley of the End, Sasuke definitively ends the cycle of hatred between Asura and Indra by making peace. Following his death, the Sage Rikudo decided to send him to another world to give a new life to the last reincarnation of Indra.
World: Highschool DxD / Shinmai Maou Testament.
Harem but not huge
Main Ship: Sasuke Uchiha / Cleria Belial
11 years before DxD Canon Events.