Koi no Cupid: Yakenohara Jin

Yakenohara Jin was a force of destruction in the war of a magical realm, and he became the demon king. However, he soon decided that his path was in a different direction; he wanted to go to the human world and act as a love cupid! After all, who wouldn't want to confide their troubles in love with a huge, violent demon creature? Jin's first case is that of teen Yoshimaru and the girl he likes, Hanai Yuriko.

(Source: MangaHelpers)