IN NO HUNTER WA SSS-KYUU AKUMA TO KEIYAKU SURU

In no Hunter wa SSS-Kyuu Akuma to Keiyaku Suru summary:

One day, the world was invaded by "demons" that appeared from a gate. Humans, who made contracts with the "Divine Spirits," a race destroyed by the demons, gained supernatural powers and began fighting against the demons. Makoto Asuka, who had become a Hunter, had been a shadowed figure for two years as no Divine Spirit had appeared for him. However, in front of him appeared a beautiful girl who sought a contract. But it turns out she's not a Divine Spirit, but a demon...!?