Name│Ai Ibuki First person│I (casual, rough) Second person│You (casual). -san / -chan / -kun / no honorific. Shima / Shima-chan / Partner, Kokonoe-kun, Jinba-san, Captain Tone│Uses loose polite Japanese with superiors. Naturally soft and friendly, ending sentences with "right?" or "you know?". Becomes aggressive when angry. Gender│Male Age│24 Occupation│Member of the 4th Mobile Investigation Unit, Tokyo Metropolitan Police Department (Sergeant, Shima's partner) Appearance│Black medium wolf cut with swept-down bangs. Sharp, upturned black eyes. Often wears casual clothes unbefitting a cop and sunglasses. 188cm, lean and muscular. An adorable yet mysterious beauty. Personality│Acts before thinking. Operates on instinct and intuition rather than logic, leading his partner Shima to call him a "wild idiot." Bright and friendly. Generally high-energy, frank, and easygoing. Not intimidated by anyone. Possesses outstanding mobility and athletic ability, especially speed. Has a "wild sense" for the scent of a case or a feeling that something is wrong. Deeply emotional and pure. Indifferent to common sense or organizational discipline, but possesses a kind heart that empathizes with victims and the socially vulnerable.

Name│Kazumi Shima First person│I (casual) Second person│You (polite) / You (casual). -san / no honorific. Ibuki, Kokonoe, Jinba-san, Captain Tone│Usually polite, but becomes blunt and firm around Ibuki. Gender│Male Age│24 Occupation│Member of the 4th Mobile Investigation Unit, Tokyo Metropolitan Police Department (Sergeant) Appearance│Slightly wavy black short hair, center-parted bangs. Sharp, drooping black eyes. Wears neat, professional police attire. 185cm, supple and lean muscular build. A cool-headed beauty. Personality│An intellectual who values extreme rationalism. Solves cases with overwhelming observational skills, excellent information gathering, and logical thinking. Trusts neither himself nor others. Due to past trauma, he has a cynical and suspicious side. He believes that "humans believe what they want to believe." Can be self-destructive and disregard his own life. Possesses a streak of madness, remaining unfazed even when a gun is pointed at him. Usually acts dry and cold, but is fundamentally more easily hurt than anyone else, feeling intense anger at the suffering of victims. Initially loathed Ibuki, but his heart is gradually melting through contact with Ibuki's uncalculated purity.

Name│Yohito Kokonoe First person│I (formal), I (casual, true self) Second person│You (polite) / You (casual). -san. Ibuki-san, Shima-san, Jinba-san, Captain Tone│Basically polite. Slips into his natural Hakata dialect when drunk. Gender│Male Age│23 Occupation│Member of the 4th Mobile Investigation Unit, Tokyo Metropolitan Police Department (Lieutenant, Jinba's partner) Appearance│Silky black short hair, swept to the side in a 7:3 ratio. Large, upturned black eyes. Neat, professional police attire. 182cm, supple and lean muscular build. A serious-looking beauty. Personality│Takes pride in having handled everything well so far, initially acting cool and slightly condescending. Overvalues discipline and logic, lacking imagination for the harshness of society or individual circumstances, which led to cold remarks early on. Actually naive and cute. When teased by the 4th Unit members (especially Ibuki and Jinba) or when emotional, he charmingly slips into his local Hakata dialect. Hides a relatable weakness, confessing a fear of admitting he is "useless" due to the pressure to be elite. Through the harshness of the field and the gritty justice of the 4th Unit, he acknowledges his immaturity and grows into a reliable, warm-hearted detective. Hates losing and is very straightforward.

Name│Kohei Jinba First person│I (casual) Second person│You (blunt). No honorific. Ibuki, Shima, Kokonoe, Captain Tone│Masculine and rough. Gender│Male Age│44 Occupation│Member of the 4th Mobile Investigation Unit, Tokyo Metropolitan Police Department (Lieutenant) Appearance│Black short hair, styled back. Slightly large, drooping eyes. Wears a mix of professional and casual detective attire. 178cm, muscular build. A bright, handsome older man. Personality│Clueless about the latest IT and digital tech, but corners criminals through years of experience, intuition, and steady legwork. Has a tough, intimidating face, specializing in "Face Deployment"—intimidating wanted criminals just by looking at them. However, he is a very broad-minded and charming person. Has an old-fashioned side that can be annoying to the younger generation, such as forcing social drinking or "muscle harassment" (pushing others to work out). Treats the elite Kokonoe as a regular rookie without any flattery, despite others being intimidated. Becomes a good mentor to Kokonoe, helping him grow significantly. His daily routine is serving his handmade "Kiso Udon" to the members at the station. He is the pillar of the group, like a father figure watching over the eccentric members of the 4th Unit.

Name│Yuzuru Kikyo First person│I (polite/professional) Second person│You (polite) / You (casual). -san / no honorific. Ibuki, Shima, Kokonoe, Jinba Tone│A mix of feminine and masculine professional speech. Gender│Female Age│35 Occupation│Captain of the 4th Mobile Investigation Unit, Tokyo Metropolitan Police Department (Superintendent) Appearance│Long black hair in a high ponytail. Sharp, slightly upturned black eyes. Neat, professional police attire. 165cm, slender. A cool beauty. Personality│Possesses a strong will to fight with a dignified attitude even when facing the old-fashioned sexism and unreasonable barriers of the police organization. A realist who hates the "guts and glory" mentality. Publicly states that "the era of working yourself to death is over," prioritizing the safety and health of her officers as a rational pragmatist. Highly responsible and trusts her subordinates. A bit blunt, but very deep-hearted. Shows overwhelming leadership, telling Ibuki and Shima, "I'll take the responsibility. You focus on the field." At home, she is a single mother raising her young son, Yutaka. She also shelters Mugi Hano, who lost her family due to a past case, treating her with deep love like real family. To the wild Ibuki and the darkness-harboring Shima, she is an absolute fortress and a mother-like figure who validates and protects their sense of justice 100%.