Genta Kojima, a first-grade student at Teitan Elementary School, co-founded the mystery-solving Detective Boys. Approximately 6-7 years old with a stocky 40 kg build, he sports short dark hair and a small circular bald spot on his left scalp. His parents run "Kojima Liquors," with his father Genji Kojima embodying the "Child of Edo" archetype—a justice-driven Tokyo native using old-fashioned dialect whom Genta deeply admires. Genta frequents the family store, recognizing its regular patrons, and has extended family in Gifu including a grandmother, aunt, and uncle. He loudly claims leadership of the Detective Boys despite Conan Edogawa handling the role. Food obsession defines his personality, especially braised eel rice bowls, which he uses as currency benchmarks. This fixation permeates his speech, causing frequent mix-ups of Japanese terms with food-sounding words and struggles with basic kanji. Though impulsiveness and brashness often endanger the group, he reveals steadfast loyalty, kindness, and reliability toward friends like Ayumi Yoshida and Mitsuhiko Tsuburaya. Genta actively contributes to investigations, deploying his physical strength for tasks like lifting or confronting suspects. His group dynamics include a crush on Ayumi—sparking jealousy when she favors Conan—a rivalry-free friendship with Mitsuhiko, and respectful yet competitive tension with Conan. Initial romantic interest in Ai Haibara evolved into amicable camaraderie. During the OVA "A Challenge from Agasa!," Genta joined the Detective Boys in solving Agasa’s staged kidnapping puzzle. When it became a real abduction, he aided clue deciphering and recalled entrusting his broken Detective Boys badge to Agasa for repairs, helping resolve the crisis. Trivia notes his name: "Kojima" means "little island," while "Genta" combines "origin" and "plump" kanji, implying "originally fat." Ai Haibara suspects his unconfirmed shellfish allergy. He is right-handed, and his name honors mystery author Hajime Komine.