Murder, Inc. is the nickname of an assassination company well-known in the underground. The corporation has branches in several major Japanese cities and handles numerous assassination and bodyguard requests throughout the series.
Murder, Inc. acquires assassins in various ways. Some employees, like Saitoh, are hired for what appear to be normal jobs and provided training to become killers. Others are hired knowing what the job entails. The company is also known to select employees who were trafficked as children and are already trained killers. Due to their practice of hiring killers from all walks of life, Murder, Inc. employees have a reputation for being unskilled assassins.
Mayor Harada Scandal Arc
Kazuki Saitoh, a recent college graduate, is one of several candidates interviewing for a position at a company in Tokyo. When the interviewer presents a surprise question and asks the interviewees what they would do if they needed to kill someone, the others simply respond that killing is wrong. Saitoh recounts a story of nearly killing someone in baseball and admits that in lacking the skills to take a life, he would have to hire someone else to kill for him, impressing the interviewer. He is given a position at the company shortly after and spends the next six months undergoing training in weapons and combat. In his first assassination assignment, he is unable to kill and is transferred to Murder, Inc.'s Fukuoka branch as punishment.
In Fukuoka, Saitoh is tasked with killing Jun Murase. Although he steels himself for his own death by company orders, the next day, Murase's body is discovered inside a burned car due to the work of former Murder, Inc. employees Reiko Asakura and Hisashi Ivanov. Saitoh's boss is impressed and congratulates him on a job well done. After the mayoral scandal, Saitoh runs from the company and has cosmetic surgery performed in order to hide.
Niwaka Samurai Impersonator Arc
Shunsuke Saruwatari is a top killer in Murder, Inc.'s Tokyo branch. Around the time he is growing tired of easy kills, his colleague Nguyen fills him in on the legendary killer of killers in Fukuoka. Saruwatari immediately decides to resign from the company and seek his own employment in his hometown, Kitakyushu, ignoring his boss' warnings that a lone killer cannot make a name for himself without an organization to back him.
At the same time Saruwatari returns to Kitakyushu, the Tokyo office sends Nguyen to Fukuoka to track down and eliminate Saitoh. Nguyen meets with the informant Enokida for information regarding the defector, and Enokida calls Saitoh to give him a warning after selling him out. Saitoh, already nearly home, spots Nguyen in time to run, frantically calling his friends for help. Xianming Lin responds to his call and meets him on a train departing Hakata Station, where he shoots Nguyen and leaves him for dead.
Nguyen, protected by a bullet-proof vest, is badly injured but alive when he reaches out to Enokida again. In order to tie up several loose ends in one move, Enokida has Shinichi Saeki perform cosmetic surgery on Yamamoto and gives him to the killer. With his job completed, Nguyen returns to the Tokyo office.
Shou Wang Arc
After two Kakyuu Association executives are murdered, roughly six killers are contracted from Murder, Inc. by Suzuki. One is hired as a bodyguard to protect Ruixi Li, and the remaining five are placed in the homes of executives who have been moved into hiding. When Saruwatari comes looking for the executive Kubota, the employee lying in wait in his house attacks. Saruwatari easily dispatches the killer, and after reviewing the camera footage, Suzuki dismisses the rest of the Murder, Inc. employees, deciding that they will be ineffective against the now-notorious assassin.
- The name Red Rum, Inc. is not mentioned in the light novels and only revealed in the manga and anime. "Red Rum" is "murder" spelled backward, and the front allows the corporation to pose as a legitimate business.