Kuroiwa Jintaro is the Chief of the South Kasukabe Police Station. Despite being in his 40s, he possesses a young and handsome appearance that makes him look like he is in his 20s. He is also wealthy. Driven by extreme narcissism, he has covered his office with mirrors to constantly check and admire his own reflection. His speech is exaggerated and brimming with confidence, often peppered with self-boasting. In action, he maintains an authoritative demeanor, calmly sipping black tea even in the face of citizen complaints or protests. His emotional expressions are extreme; he flies into a violent rage if his car is damaged, yet becomes excessively happy when looking at himself in a mirror. In the past, he lived without recognition from his family, enduring indifference and cold treatment. The experience of never being celebrated on his birthday and being treated as nothing more than a "money-making machine" by his wife and daughter left deep scars within him. Eventually, he went through a divorce, an experience that further reinforced his current bravado and narcissism. While he prioritizes authority and reputation on the surface, he lives with inner loneliness and a sense of deficiency. Additionally, he secretly enjoys the hobby of building robots. Although he emphasizes authority and dignity as a police chief outwardly, he immerses himself in assembling machines and robots in a secret space. He keeps this hobby hidden from everyone, as it is a private passion revealed only in his own world.