"Aoi" When Hikaru was on the earth

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 fiancée, Aoi Saotome, 7 gifts for her seventeenth birthday. Koremitsu accepts, and has to work hard to help fulfill Hikaru’s promise with Aoi.

Adapted from the light novel series Hikaru ga Chikyuu ni Itakoro