Kanan-sama wa Akumade Choroi is a Manga/Manhwa/Manhua in english language, SUGGESTIVE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Kanan is a demon hiding in a high school in the human world to feed on the souls of humans. She sets her sights on a single high school boy, but somehow ends up in a lovers contract with him!? Kanan, who has never been in love, is now filled with new feelings! The romantic comedy of a pure-hearted demon's first love, begins!