Saitoh (斉藤, Saitō) is a recent university graduate employed by Murder Inc. who is transferred to the Fukuoka Branch after failing an assassination assignment handed to him. After the events of the first volume of the light novel he leaves the assassination business behind and resumes a normal, quiet life.
Saitoh has brown and well-kept hair and is usually seen in a formal brown business suit in illustrations.
He is often described as timid and fearful and is prone to near tears under stressful situations. While he had been taught all the techniques and skills in hand-to-hand fighting or using knives at Murder Inc. he has nearly forgotten all of that knowledge. Due to his inabilities he will often thus depend solely on others to help him resolve issues such as handling assassins sent after him or an incident he was framed for.
Saitoh does have a huge interest and love for baseball. In his narration in the light novels he frequently makes comparisons of current situations he is facing to particular set-ups that occur in baseball games. Because of an incident that happened in a game where he accidentally hit the batter in the head with a pitch he made he developed the 'yips' and has become unable to throw a ball, afraid he would end of hitting and injuring someone the same way as in the past.
Saitoh was part of a veteran school in the Kanto region of Japan and participated in their baseball club, which he was the ace pitcher of the team. His school team managed to make it to enter Hanshin Koshien, where the Japanese National High School Baseball Championship is held. During one of the matches, however, Saitoh pitched a ball that hit the batter in the head, which ended with the batter hospitalized and in a coma. Saitoh received trauma from the incident and, unable to pitch, resigned from the team and continued on solely with his academic career.
Light Novel Volume 1Edit
Saitoh is accepted to an interview for a job position at a corporation in Tokyo, completely unaware he is applying to an assassination company, Murder Inc. He manages to impress one of the interviewees by reciting the time he almost killed someone at Koshien in the past. He receives an offer two weeks after the interview. When he arrives at the company he is surprised of their true operations. After months of undergoing training he is given his first assignment to assassinate a political figure but can't muster the courage to do so. Because of his failure, he is directed by his superior to transfer to the Fukuoka Branch the following day or risk being eliminated by the organization.
Once arriving in Fukuoka City he gets situated and then heads to meet his new superior who gives him a fake ID with the name Takeda Itou and an assignment to kill Jun Murase. After receiving the details of his target, Saitoh heads to Murase's residence and waits for Murase to return home to complete the task. Before he can do that, he encounters Jiro and his helper Misaki and unaware that they also have come to capture Murase, he gives his target's name instead of his own when asked, resulting in him being kidnapped by the two.
He wakes up in an empty warehouse, tied up and with his mouth sealed with tape. Jiro and Martinez are there. They introduce themselves as avengers and proceed to torture a high school boy who murdered a cat in a cruel way in front of Saitoh. Once they're done, they kill the boy by cutting off his head. Jiro prepares to beat Saitoh up, assuming Saitoh is Murase who beat a man to death. He removes the tape from Saitoh's mouth to have him confess. Once Saitoh can speak, he tells Jiro that he's actually an employee of Murder Inc. who was sent to kill Murase and asks him to take his business card out of his pocket as proof. Jiro apologizes, lets Saitoh go and offers him his own business card.
Saitoh goes back to the hotel where he's been living since arriving in Fukuoka and goes to sleep. When he wakes up, he receives a call from his superior, congratulating him for killing Murase and presenting it as an accident. Saitoh calls Jiro to ask if the avengers killed Murase but gets to know that they did not. Still not knowing who actually killed Murase or if it was really an accident, Saitoh goes to the entertainment district and decides to use some of the money he's been paid for Murase's death to have fun there.
The next morning he wakes up at the hotel and realizes a dead woman is on the bed next to him. He recalls that he was very drunk the previous night and a woman different from the dead one approached him but doesn't remember anything else. He flees the hotel room in a hurry.
Some time later, while wandering around the city, he learns from a TV broadcast that the dead woman's body has been found and he is a murder suspect under his fake name Takeda Itou. He decides to go to Bar Babylon where Jiro is the manager and explains the situation to Jiro who tells him he must have been set up. Saitoh asks Jiro to avenge him by placing the blame back onto the real culprit and offers to pay him with the money he got for Murase's death.
Saitoh stays hidden at the bar while Jiro leaves. When Jiro comes back, he tells Saitoh that he found out who set Saitoh up and takes him to an apartment building in the city. Xianming Lin and Zenji Banba (in the Niwaka Samurai disguise) are already there. They're waiting for the targets, Reiko and Yusuke, who locked themselves inside an apartment, to call a cell phone that Banba has taken from their associate. The phone rings. Banba talks to Reiko, letting her know he's come for Yusuke, and the door of the apartment opens and Reiko runs out. Saitoh recognizes her as the woman whom he met the previous night. Jiro grabs Reiko and tells her that to avenge her having framed Saitoh, she will be made to take the blame for all the incidents, and renders her unconscious.
Lin and Banba go into the apartment to look for Yusuke but can't find him until he ambushes them with a gun. Jiro can't help them because he's holding Reiko, so Saitoh grabs a signed baseball from the cupboard and throws it at Yusuke, incapacitating him. Jiro asks Saitoh to join the Hakata Tonkotsu Ramens baseball team as a pitcher then, but Saitoh is hesitant.
Jiro takes him to a nearby hotel and gives him the bussiness card of Saeki's cosmetic surgery clinic and suggests to Saitoh to change his facial features. Saitoh sees this as an opportunity to escape both the murder charges and Murder Inc. and heads to the clinic some time later. After the operation, he calls Jiro and accepts the pitcher's position.
During his first game with the Hakata Tonkotsu Ramens team, he's hit on the head with a baseball by the opposing pitcher while in the batter position. He realizes that the pitcher looks similar to the batter whom he hit with a ball years ago and that Jiro and Misaki are smiling, seemingly having set up the incident.
- Saitoh's Murder Inc. business card in the anime lists his first name as Kazuki.