Dr. Kenzo Tenma is a renowned Japanese brain surgeon working at a leading hospital in Germany. One night, Dr. Tenma risks his reputation and career to save the life of a critically wounded young boy over that of the town mayor who had been planning to support the hospital financially. A string of mysterious murders begin to occur soon after the operation, and Dr. Tenma emerges as the primary suspect despite no incriminating evidence. 
 
A doctor is taught to believe that all life is equal; however, when another series of murders occur in the surgeon's vicinity, Dr. Tenma's beliefs are shaken as his actions that night are shown to have much broader consequences than he could have imagined. Leaving behind his life as a surgeon he embarks on a journey across the country to unravel the mystery of the boy he saved.

[Wiki (jp)](https://ja.wikipedia.org/wiki/金子由之)

Everyone faces uncertainty at some point in their lives. Even a brilliant surgeon like Kenzo Tenma is no exception. But there’s no way he could have known that his decision to stop chasing professional success and instead concentrate on his oath to save peoples’ lives would result in the birth of an abomination. The questions of good and evil now take on a terrifyingly real dimension.
 
Years later, in Germany during the tumultuous post-reunification period, middle-aged childless couples are being killed one after another. The serial killer’s identity is known. The reasons why he kills are not. Dr. Tenma sets out on a journey to find the killer’s twin sister, who may hold some clues to solving the enigma of the “Monster.”
 
(Source: Viz Media)

Niwashi