Kenzo Tenma

Dr. Kenzo Tenma is the main protagonist of the Monster series.

Dr. Kenzō Tenma is a Japanese neurosurgeon working at the Eisler Memorial Hospital in Düsseldorf. At the beginning of Monster, he is the Head of Neurosurgery who was favored by the department's director, Heinemann, for his prodigious surgical skills and was even offered Director Heinemann's daughter Eva for marriage. When it came to a young boy with a bullet wound, Dr. Tenma was about to prepare the operation for him when Chief of Surgery Dr. Oppenheim and a call from Director Heinemann told Tenma to work on Mayor Roedecker (who collapsed at his holiday home). Tenma told Director Heinemann that he is the only one who could operate on a young and asked Director Heinemann to have Dr. Boyer handle the mayor, but Director Heinemann ignored his request and ordered him to operate on the Mayor. After a crisis of conscience, he chooses to save the life of a young boy instead of Mayor Roedecker. He is then scolded afterwards by Dr. Boyer and Dr. Oppenheim for not working on the mayor, who died as a result of the doctors having to scramble to cover for Tenma at the last minute. At a banquet, Dr. Tenma begged for forgiveness from Director Heinemann who partially forgave him while stating comments that blacklisted Dr. Tenma, Eva rescinding her marriage, and Dr. Boyer gaining Tenma's position as Head of Neurosurgery.

Some weeks later, Dr. Tenma gets word from the visiting policemen that Director Heinemann, Dr. Oppenheim, and Dr. Boyer are mysteriously killed. Because of the three deaths and some transfers of some of the doctors, the Chairman of the Board ended up giving Dr. Tenma the position of Chief of Surgery. It is only after nine years that Dr. Tenma learns the perpetrator of Director Heinemann's murder and the recent death of Adolf Junkers is none other than the boy he saved years before, Johan Liebert. Plagued by guilt, he resolves to find Johan and end the life of this "monster" he feels responsible for creating while evading Inspector Heinrich Lunge, who suspects him of the murders committed by Johan.

Despite his mission, Dr. Tenma is a humanitarian who genuinely cares about the lives of others. These acts of kindness make him very influential with the people he meets. Not much is known about Tenma's childhood; however, when he was growing up in Japan, he was constantly getting picked on and had a habit of wetting his pants. This earned him the nickname of "Sissy Pants Tenma". As well, Kenzo's father and brother were also doctors, though Tenma was not close to his family, and his family ties have grown weaker as he had not been back in Japan since he left to Germany. It is unknown how much time passed between Tenma becoming a certified doctor to when he started as an attending surgeon at Eisler Memorial Hospital. However, it soon became evident to his superiors that Kenzo was probably the best neurosurgeon on staff, and he would quickly be promoted to Chief of Neurosurgery around the same time he met Eva. Tenma also has some acquaintances from Japan who occasionally visit him while on business, but it is not known how close his friendship with these people is. In his journey to kill Johan, he comes incredibly close on a number of occasions only to have Johan slip away.

This ends up leading him to the final confrontation with Johan in Ruhenheim. When Johan wants Tenma to kill him, he tries to threaten Wim when the child's drunk father Herbert ends up mistaking Johan for a monster and shoots him. After Johan had been picked up by the ambulance, Dr. Tenma ended up treating the wound. Eventually, Dr. Tenma was cleared of all charges. He later joins Doctors Without Borders and learns from Otto Heckel where the mother of Johan and Anna is located. Tenma later visits a comatose Johan in a police hospital.