Black Jack (TV)

Well, it seems like Mushishi manga was partially inspired by Black Jack and I guess that's pretty much clear, since they both are episodic, focused on extraordinary main hero who travels different places and tend to help others in trouble with his skills and knowledge (being doctor in one case and mushi specialist in other). Though there are certain differences, like Mushishi setting has more mystique and fantasy world rather than almost real world in Black Jack settings, and Dr. Black Jack having more deep and controversial personality than Ginko from Mushishi who is not so emphasized, similarities are pretty much straightforward. 

Both are episodic series about a slightly mysteriously man that travels the globe and helps people in various situations. Both shows have next to no recurring characters, aside from the main protagonist(s). 

Want to learn about the studies and anatomy of the human body? You're in luck because both animes feature elements such as mental illnesses, physical conditions, disabilities, and how the body works! 

Main protagonists who were once well respected for being top in their fields (medical/art restoration) now increasing submerged into shady dealings due to the greed and unrelenting ambitions of their peers; they've chosen to embrace and live in the underground upon realizing that the ideals once sought by their youthful selves are made impossible by the deep darkness within the human heart. Still, unable to completely relinquish their beliefs, they chosen to follow their own path; separate from "good" and "bad". Both also have younger female assistants who seemingly love and take pride in their work. 

About a strong-willed, fugitive doctor, and the high drama he comes across as he seeks to settle a horror from his past. 

Both feature an intelligent adult with a young companion meeting people and helping them. Both can be very emotional and philosophical.  

Very similar strong-willed main characters who fight for what they believe in.