Hiroshi Agasa, an inventor and engineer, lives next door to the Kudo family. He appears as a middle-aged man of 160 cm height with a slightly overweight build, a bald head, silver hair, thick eyebrows, a mustache, and a bulbous nose, usually wearing round glasses and a lab coat. Agasa attended Teitan Elementary and Okuho Middle School, meeting his first love, Fusae Kinoshita, in sixth grade before her family moved away. His relatives include deceased parents, a great-uncle Kurisuke Agasa who died 50 years ago at age 38, a great-aunt Teiko Agasa who died a year ago at 76, an unnamed cousin, and that cousin's granddaughter. Agasa's life shifted dramatically upon encountering Shinichi Kudo shortly after Shinichi was transformed into a child by the APTX 4869 poison. Initially skeptical, Agasa became the first to learn Shinichi's true identity after witnessing his deductive skills and hearing personal details only Shinichi knew. He cautioned about the Black Organization and helped Shinichi establish the alias Conan Edogawa. Agasa invented numerous gadgets to aid Conan's investigations, such as communication badges and a stun-gun wristwatch. He enrolled Conan at Teitan Elementary, leading to the formation of the Detective Boys, whom he frequently chaperones on trips that often involve criminal cases. Later, he provided shelter to Shiho Miyano after her escape from the Black Organization, learned her identity, and helped her become Ai Haibara. Agasa also informed Shinichi's parents, Yusaku and Yukiko Kudo, about their son's condition. Agasa maintains a jovial and caring personality, leveraging community connections to plausibly explain Conan and Haibara's presence as children of acquaintances. He exhibits paternal affection toward the Detective Boys, often organizing activities for them despite their tendency to encounter crimes. Professionally, he holds patents for inventions like video games, funding his lifestyle and laboratory, though many creations prove ineffective or destructive. His notable possessions include a yellow Volkswagen Beetle, unreliable but retained for over a decade, and a Persian rug involved in a theft investigation that prevented its sale. Agasa possesses exceptional luck in winning food-related prizes and games of chance. In *The Scarlet Bullet*, Agasa assists the Detective Boys in attending the Hyper Linear train's unveiling event tied to the World Sports Games (WSG). He devises a quiz to determine which six of the seven attendees (Conan, Haibara, the Detective Boys, and Ran Mouri) would receive train tickets, though he is excluded from participation. When Conan and Ran redirect the Detective Boys to a safer activity due to kidnapping risks linked to the WSG, Agasa supports the change. His role includes providing logistical aid and maintaining the children's safety amid the unfolding crisis involving abductions mirroring an incident 15 years prior in Boston. Agasa's relationships are multifaceted: he shares a familial bond with Conan, collaborates on inventions and cover-ups with Haibara (who often monitors his diet), and maintains friendships with Yusaku Kudo and law enforcement figures like Inspector Megure. His reconnection with Fusae Campbell, now a fashion designer, hints at potential romantic development after decades apart. Agasa is aware of the Black Organization's existence through Conan and Haibara but avoids direct confrontation, focusing on support and protection. He has a distinctive mole on his buttock. Fan speculation suggesting he leads the Black Organization has been dismissed by the author. The etymology of his name derives from Agatha Christie.