18+ Chotto dake Ai ga Omoi Dark Elf ga Isekai kara Oikaketekita

Hinata did it. He got reincarnated into another world, took up the mantle of Hero, and slew the dreaded Demon Lord alongside his party of fellow adventurers. As his reward, he's returned to Earth to resume a normal life. Or it would be if it wasn't for the fact that his dark elf companion Mariabelle decided to travel to Earth to come and live with him! Now she uses her arcane talents to ward off any potential romantic rivals and capture Hinata's affection.

(Source: Seven Seas Entertainment)