Kōshirō Daimon is a police officer and the younger twin brother of Kenshiro Daimon. The two work as a pair, often patrolling together and stopping vehicles. Due to unspecified family reasons, Kōshirō harbors a dislike for taxi drivers in general and holds particular animosity toward Hiroshi Odokawa. He is a natural talker, prone to speaking without thinking, and has an absent-minded quality that sometimes undermines his effectiveness as an officer. Despite these traits, Kōshirō possesses a strong sense of justice and genuinely believes in doing the right thing. He places complete and naive trust in his older brother, unaware of Kenshiro’s corrupt dealings, such as accepting bribes from gangsters. In the story, the Daimon brothers are frequently seen pulling over Odokawa’s taxi as part of their investigation into a missing high school girl, though Kōshirō’s role is largely reactive and overshadowed by his brother’s more proactive and dishonest actions. His motivations stem from a sincere desire to uphold the law and protect the innocent, but his gullibility and reliance on Kenshiro prevent him from seeing the full picture. Over the course of the events in the Odd Taxi series and the film Odd Taxi: In the Woods, Kōshirō shows little personal development; he remains an earnest but somewhat oblivious figure whose steadfast loyalty to his brother ultimately blinds him to the corruption around him. His notable abilities are limited to standard police duties, and he does not exhibit any exceptional physical or investigative skills beyond his role as a patrol officer.