Aoi - Hikaru ga Chikyuu ni Itakoro

The story starts with the death of Hikaru Mikado. That guy was a natural charmer, a "harem king", but had no real male friends. After he died, he became a ghost, a soul, but Koremitsu Akagi can see him. Koremitsu though, isn't really like Hikaru. His red hair and his evil-looking eyes make him look as a delinquent, even though he is very kind inside. Hikaru asks him a favour: he wants to fulfill a promise, which he couldn't fulfill anymore. The promise was to give his girlfriend and fiance, Aoi Saotome, seven gifts for her seventeenth birthday. Koremitsu accepts, and has to work hard to help fulfill Hikaru's promise with Aoi.