Jinpei Matsuda served in the Tokyo Metropolitan Police Department’s Explosive Ordnance Disposal Division. Four years prior to *The Bride of Halloween*, his partner Kenji Hagiwara died during a revenge plot by a serial bomber whose own partner had perished in an accident. The tragedy precipitated Matsuda’s temporary transfer to the First Division under Inspector Megure, pairing him with rookie detective Miwako Sato. Though his blunt demeanor sparked initial tension, Sato gradually grew emotionally attached to him. Three years before the film’s timeline, Matsuda confronted the same bomber during an investigation. A device planted on an amusement park Ferris wheel trapped him inside, where the bomber disclosed a second hidden bomb in the city. Its location would unlock as the Ferris wheel’s timer expired. Choosing to secure the second bomb’s coordinates over personal survival, Matsuda relayated the information to Sato via text seconds before the explosion claimed his life. The message, preserved on Sato’s phone, became etched into her memory as a permanent testament to his sacrifice. In *The Bride of Halloween*, Matsuda’s legacy looms over a simulated wedding drill involving Sato and Wataru Takagi. When Takagi appears to mimic Matsuda’s self-sacrifice, Sato spirals into visceral flashbacks of the Ferris wheel tragedy. Simultaneously, the resurgence of bombings by the escaped serial bomber—now linked to the group Plamya—ties directly to Matsuda’s unresolved case. Clues from his final actions prove pivotal, while his police academy peers, Rei Furuya and Hiromitsu Morofushi, assist in piecing together the conspiracy. His influence permeates both Sato’s internal struggles and the operational unraveling of the plot. Matsuda’s personality fused untamed intensity with underlying compassion, evoking the duality of a Shiba Inu’s loyalty and a Doberman’s ferocity. His visual and behavioral design echoed Spike Spiegel from *Cowboy Bebop*, mirroring the character’s sharp aesthetics and roguish charm. Though deceased before the film’s main events, his decisions and relationships persistently shape the trajectories of allies and adversaries, anchoring Sato’s emotional arc and the resolution of intertwined bombing mysteries.