Hiroshi Agasa, Shinichi Kudo's next-door neighbor and family friend, is an inventor and engineer. He earns a living through various patents and inventions, including video games enthusiastically tested by the Detective Boys. While many inventions prove useless or damage his laboratory, his successes fund a large house and its necessary rebuilds. Agasa has known Shinichi and Ran Mouri since their childhood. He attended Teitan Elementary and later Okuho Middle School, meeting Fusae Kinoshita in sixth grade before she moved away that fall; his family also relocated from Tokyo to the countryside soon after. His relatives include a great-uncle, Kurisuke Agasa, a rich accountant who died fifty years prior at age 38, and a great-aunt, Teiko Agasa, who passed away a year ago at age 76. He also has an unnamed cousin and a cousin's granddaughter of marriageable age. Jovial, caring, and outgoing, Agasa has many community friends, aiding his cover story that Conan and Haibara are children of acquaintances. Highly intelligent with at least one advanced degree, he takes pride in inventions sometimes used in official events. Though a bachelor, he shows paternal affection towards the Detective Boys, frequently chaperoning their trips—which often inadvertently involve criminal cases. He possesses remarkable luck in games of chance, frequently winning food tickets and lotteries. His favorite foods are pasta and tomato juice. Physically appearing older than his 53 years, he has a slightly overweight frame, a bald crown, silver hair, thick eyebrows, a mustache, and a bulbous nose. He typically wears round glasses and lab attire. After Shinichi Kudo was transformed into a child by APTX 4869, Agasa was the first person Shinichi encountered and entrusted with his secret. Agasa advised caution against the Black Organization and helped establish Shinichi's new identity as Conan Edogawa. He invented numerous gadgets for Conan's detective work, including the Detective Boys' badge walkie-talkies, flashlight-watches, voice-changing bowties, and soccer ball shoes. 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 doorstep, Agasa took her in, learned her identity, and helped her become Ai Haibara. He subsequently informed Shinichi's parents about their son's condition. Agasa maintains a close, almost familial bond with both Conan and Haibara. Haibara often acts protectively, shielding him from danger and managing his diet to improve his health. Their relationship deepens with Agasa's past acquaintance with Haibara's parents, particularly her father, Atsushi Miyano, though he was unaware they had children. Beyond providing gadgets, Agasa actively supports Conan's investigations, using voice-altering devices to mimic others. He owns a yellow Volkswagen Beetle with a built-in television, though it is notoriously unreliable. A Persian rug he owns could fund a car replacement but remains unsold due to police investigation involvement from a prior theft. Aware of the Black Organization through Conan and Haibara, Agasa assists in strategizing against them while avoiding direct confrontation. His childhood connection with Fusae Kinoshita (now Campbell) resurfaces when the Detective Boys help him decipher clues leading to a reunion, hinting at a rekindled relationship. Referred to as "Professor" (Hakase) by most characters, including Conan, Haibara, and the Detective Boys, Yusaku Kudo occasionally nicknames him "Professor Sunshine." Agasa uses honorifics like "-kun" for children and "-san" for adults, such as Inspector Megure. He has a distinctive mole on his buttock with a protruding hair, used by Conan to prove his identity during their first meeting. Creator Gosho Aoyama has explicitly denied fan theories suggesting Agasa could be the Black Organization's leader. Agasa remains a grounding presence, providing technological and emotional support to the protagonists.