Jinpei Matsuda is a former detective of the Tokyo Metropolitan Police Department who, by the time of the film The Bride of Halloween, has already been deceased for three years, having died at the age of twenty-six while on duty. Prior to his transfer, Matsuda was a member of the police bomb disposal unit. He was reassigned to the First Investigative Division, specifically to the Violent Crimes unit, where he was partnered with Miwako Sato. This transfer was made by his superiors who feared his personal vendetta against a serial bomber, the same culprit responsible for the death of his best friend and former bomb squad partner Kenji Hagiwara, would cloud his judgment. Matsuda ultimately lost his life to this same bomber while attempting to disarm an explosive on a Ferris wheel at an amusement park. As the timer counted down, he used his final moments to send a text message to Sato revealing the location of a second bomb hidden elsewhere in the city, sacrificing himself to save countless innocent lives.

Matsuda was a man of notable contradictions, presenting a rough and abrasive exterior that concealed a deeply principled and caring nature. Miwako Sato recollected that he was a foul-mouthed and cocky individual who seemed to rush headlong into danger without a second thought, a personality best described as a blend of a ferocious Doberman and a loyal Shiba Inu. Despite his blunt and uncooperative demeanor, which initially made him unpopular with his fellow detectives, he possessed a profound sense of duty and a wild but undeniable inner kindness. He was a man of action, known for being unstoppable once he decided on a course, even if it meant taking injuries to stop a suicide or catching a knife with his bare hands. This cool, self-sacrificing spirit, where he weighed the safety of citizens above his own life, became a defining feature of his legacy.

Matsuda’s primary motivation, particularly in the years before his death, was vengeance for the murder of his friend Kenji Hagiwara. Hagiwara had been killed seven years prior by a serial bomber, and Matsuda was determined to avenge him. This personal quest was the driving force behind his repeated requests to be transferred to the unit handling the bomber. His initial motivation for joining the police force, however, was far from noble. As revealed in stories from his police academy days, Matsuda became an officer for the purpose of assaulting the superintendent general. This stemmed from a childhood trauma where his father, a professional boxer, was falsely arrested by the police for a murder he did not commit. While the charges were eventually dropped, the arrest caused his father to miss a championship match, leading to the ruin of his career and a descent into alcoholism.

In The Bride of Halloween, Jinpei Matsuda’s role is that of a specter from the past whose actions continue to drive the present-day narrative. The entire plot is set in motion when a bomb victim is found carrying one of Matsuda’s old police business cards, forcing the police to re-examine his final days. His memory looms large, particularly over Miwako Sato, who is still haunted by his death. The film explores the events of the week leading up to his demise, including a previous confrontation with the film's main antagonist where he demonstrated his bomb disposal prowess. His final message and sacrifice remain a pivotal emotional touchstone for Sato, influencing her actions and resolve throughout the investigation.

Several key relationships define Matsuda’s character. His most significant connection was with his partner, Miwako Sato. Although she initially found him aloof and direct, they grew close during his brief time in her division, and she ultimately fell in love with him. His death haunted her for years, and she kept his final text message on her phone as a treasured memento. His other crucial relationship was with his police academy classmate, Rei Furuya, also known as Tooru Amuro. At the academy, Matsuda and Furuya were rivals who often clashed, even engaging in a fistfight that left both of them bloodied. This antagonism eventually gave way to a deep mutual respect and friendship, with Matsuda personally teaching Furuya the skills of bomb disposal. His friendship with Kenji Hagiwara was foundational; despite Hagiwara’s death, Matsuda continued to send emails to his account, unable to let go of his promise to avenge him. He also maintained strong bonds with fellow classmates Wataru Date and Hiromitsu Morofushi.

Matsuda displayed notable development, particularly between his hot-headed, seemingly reckless youth and his composed, professional final days. At the police academy, he was depicted as a frivolous and troublesome figure who would get into brawls with his classmates, driven by a childish grudge against the police force. The death of his best friend, Hagiwara, was the pivotal event that transformed him. The need for revenge channeled his raw energy and skill into a focused, if still volatile, pursuit of justice, eventually shaping him into the capable and self-sacrificing detective he became. He exhibited an uncommonly wide range of exceptional abilities. He was a master of bomb disposal, capable of deconstructing and dismantling complex explosive devices, often in under three minutes, and could identify bomb components at a glance. His martial arts proficiency stemmed from boxing, a skill he learned from his professional boxer father, and he was strong enough to fight Rei Furuya to a standstill. Matsuda possessed a sharp and agile intellect, capable of rapid deductive reasoning. He could quickly type and send vital information, as demonstrated by his final message that identified a bomb's location in just three seconds. Furthermore, he was a mechanical savant with a natural gift for repairing and reassembling everything from firearms and cars to cell phones.