The Shadow Hunter Makes a Deal With an SSS Class Demon is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

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...!?