Hiroshi Agasa, an inventor living next door to Shinichi Kudo's family home, shares a long-standing childhood friendship with Shinichi and Ran Mouri. He attended Teitan Elementary, where he met Fusae Kinoshita. Agasa's family includes deceased parents, extended relatives like his gadget-loving great-uncle Kurisuke Agasa (deceased decades prior), recently deceased great-aunt Teiko Agasa, an unnamed cousin, and that cousin's granddaughter. After Shinichi's transformation into a child due to the APTX 4869 poison, Agasa became the first to learn his true identity, offering immediate sanctuary. He warned about the Black Organization and facilitated Shinichi's new identity as Conan Edogawa. Agasa invented numerous specialized gadgets for Conan's investigations, including voice-changing devices, tracking equipment, and enhanced footwear. He also enrolled Conan at Teitan Elementary, leading to the Detective Boys' formation. Later, when Shiho Miyano escaped the Black Organization and collapsed near his home, Agasa took her in, learned her identity, and helped establish her persona as Ai Haibara, subsequently informing Shinichi's parents. Agasa frequently chaperones the Detective Boys, their excursions often intersecting with criminal cases. His residence has been rebuilt multiple times due to destructive incidents involving his inventions; one notable failure during an upgrade to Conan's ball-dispensing belt caused an explosive crater in his backyard. Despite mishaps, inventions like the "Tropical Rainbow" explosive gained official recognition. He owns a yellow Volkswagen Beetle with a built-in television, prone to mechanical issues. A valuable Persian rug he owned became a target for thieves after he posted a video online. Physically, Agasa is slightly overweight with a bald crown, silver hair, thick eyebrows, a mustache, and a bulbous nose, typically wearing round glasses and a lab coat. His personality is jovial, caring, and outgoing, aiding in explaining Conan and Haibara's presence. He exhibits paternal behavior toward the Detective Boys, prefers pasta and tomato juice, and has his diet monitored by Haibara for health reasons. Agasa displays remarkable luck in games of chance and contests, frequently winning food tickets and prizes. Aware of the Black Organization, Agasa actively supports countermeasures while avoiding direct confrontation, using his residence as a safe haven for planning. He shares a close bond with Haibara, who exhibits protective instincts; they later discovered his prior acquaintance with her parents. Agasa's reunion with Fusae Campbell, now a fashion designer, hints at potential romantic development. He interacts regularly with law enforcement, assisting cases through his inventions or incidental involvement.