Shigematsu has short, dark brown hair and a mustache. He is usually seen wearing a suit.
He is a calm and patient man who has a high standard for justice. Well-acquainted with the high crime rate and the shady business carried out in the underbelly of Fukuoka, he has adopted the standpoint that in order to fight against criminals, it is necessary to become a criminal himself. As such, he frequently gives jobs to Banba to carry out when he cannot pursue a case beyond his public disposition.
Mayor Harada Scandal ArcEdit
Shigematsu meets Banba in Kego Park and provides him with confidential information on an investigation regarding the murder of another detective, his senior Takeda. He requests that the private detective look into the matter. After Banba accepts the job, Shigematsu hands over a photo of Mayor Harada at Club Miroir that the now-deceased detective had been investigating.
A few days later, Shigematsu meets up with Banba at the batting cages to ask about his progress in the case. Banba informs him that the woman they saw with the mayor is a former employee of Murder, Inc. as well as his suspect for the detective's murder. When Banba tells him he left bait by heading to Club Miroir to directly ask about the mayor's visit, Shigematsu is concerned and warns Banba that a hitman could possibly be sent after him for that.
The following day, Shigematsu is called by Banba to look into the recent murder of Qiaomei Lin and is summoned to Banba's office to talk with him and Xianming Lin. After seeing the strangulation marks on Lin's neck, Shigematsu is convinced that Ivanov is the man responsible for his colleague's death. He shows the pair data of the investigation into the suspect for Qiaomei's murder, Takuya Itou, but they agree that Itou is unlikely to be the actual killer.
That night, Shigematsu and his team arrive at the Kakyuu Association's offices in Suzaki City shortly after the Niwaka Samurai cuts down everyone present. He and his team handle the cleanup of the bodies.
Niwaka Samurai Impersonator ArcEdit
The detective provides Saitoh a place to stay after Murder, Inc. sends Nguyen to kill him. He is supposed to pick Saitoh up and bring him home after his final convenience store shift, but George Gondo attacks Saitoh at work.
During a practice game in late June, Shigematsu and Jiro have to break apart Lin and Banba when they start to fight. Though the poor playing and bickering have the team's spirits down, Genzo's suggestion of a punishment game forces them all to work hard, and Shigematsu hits a home run in the final inning. He later attends the Ramens' pre-primaries get-together, where he and Enokida discuss Long Fang Wang's murder and autopsy results, deducing his cause of death.
Shou Wang ArcEdit
Shigematsu is one of many officers at Byeong-Hee Kim's apartment building after his body is found in the parking garage. He pulls Banba and Lin to the side to inform them of Kim's murder and ties to the mafia, acting exasperated when the pair speak openly about killing.
He attends the Ramens' weekly practice the next day, noting how running is becoming more difficult as he ages, and joins the rest of the players present in teaching Lin the team's signs. The following night, Shigematsu stops by Gen-chan for dinner and asks Lin about the deaths of two older men named Hiyashi Noriaki, whose names are spelled like his. After giving him the details of the murders, he shows Lin the case file photographs. Lin has a sudden realization, and when he runs off, Shigematsu threatens to arrest him for not paying for his ramen.
A month later, the Ramens attend a fireworks festival together in the eastern ward. Shigematsu and Saitoh arrive ahead of the rest of the team to save a spot for their group.
Not long after the fireworks festival, Shigematsu learns that Saitoh has been arrested by the cybercrime division, and he informs Enokida, who vouches to an associate in the cybercrime division on his behalf. The following day, the detective has dinner with Banba to discuss Yusuke Aoyagi's death and recent history, confirming that Aoyagi had a short history of being a problem at work and had committed suicide, admitting that something about the case seems off.