Dr. Duo

For Shinonome Keisuke, high school student Kotone Tasuku is the only person in the world whom he can communicate with. Once a brilliant surgeon, Shinonome passes away at a young age, only to wander the world as a ghost, a ghost that only Tasuku can see and talk to. When an accident leaves Tasuku’s hot childhood friend Takeuchi Mai’s younger brother severely injured, the only way that he can survive is if Shinonome and Tasuku work together to become the most unusual and possibly talented pair of emergency surgeons the country has ever seen!

(Source: MangaHelpers)

Included one-shot:
Volume 1: Little Big Doctor (pilot)