Histoire
As long as hearts exist inside people, there will always be those who suffer. And then something "strange" enters their mind and causes a strange disease to manifest itself in the body. The illness, which is called a "mystery disease" is unknown to most, but certainly exists. There is a doctor and apprentice who fights the disease, which modern medicine cannot cure. His name is Ramune. He acts freely all the time, is foul-mouthed, and doesn’t even look like a doctor!
Synopsis via AniList (en anglais).