Love Riron

Loser Yarahata Kanji can't even have a normal conversation with a girl let alone have any kind of relationship with one. But one day a ghost named Aiya appears and declares that he has been tasked with the mission to change Kanji's life. At this rate, the Yarahata name will not live on so Aiya will become a love doctor and coach him on how to develop relationships with girls.

The first hurdle comes when he starts a part time job at a convenience store and sees that his co-worker is a hot girl named Yoshizato Saki who also happens to be the store owner's daughter. With the help of Aiya, Kanji, although stumbling along the way, has a conversation with her and builds a relationship. But he has miles to go if he wants to be the kind of person that can date beautiful women.

(Source: MangaHelpers)