Dr. Tezuka was known as the Godfather of Manga. Not so much as it's originator, but really the person who brought into a serious literary form. His years in medical school had primed him to write mostly from a physicians point of view. And most of his subjects centered around disease.
One of his most popular was Ode To Kirihito, which focused on a doctor who is infected with a disease that causes the patient to develop animal type features, which the doctor himself ends up contracting.
He had a method of keeping his characters pretty simple and expressionistic, while rendering detailed, almost photo like backgrounds. Another volume of his work which is recommended, is his account of the Life Of Buddha titled 'Buddha' which he spent 8 years on, and is compiled in 8 Volumes.