Shinnosuke Kamei, a detective in Tokyo’s Modern Crime Prevention Task Force, shirks responsibilities in favor of leisure, his apathy contrasting sharply with occasional bursts of motivation. Sporting sandy blonde spikes and yellow-brown eyes, his tall frame dons a yellow sweater with pink motifs over a white shirt, paired with light blue pants and a blue blazer outdoors.

His indifference to duty dissolves when Motoyama, a security division employee he admires romantically, becomes involved in cases. This sparks abrupt shifts from lethargy to participation, exemplified during a Classic Car Festival mission where he dramatically feigned death via paint bullet to confess feelings for her—a ploy cut short by colleagues.

Haru Kato, a diligent peer, frequently counters Shinnosuke’s evasiveness, dragging him into action. Their exchanges reveal his reluctant competence: he discloses a Ginza bar tied to First Division officers or identifies a suspect’s social media mid-interrogation, offering minimal effort unless pressed.

Prone to watching questionable content on office devices and plotting early exits, he nonetheless exhibits flashes of shrewdness—spotting suspicious vehicles during stakeouts or calculating financial risks from collateral damage. His name, blending "turtle," "well," "new," "this," and "help," hints at a persona straddling inertia and unexpected utility.