Professor Agasa, also known as Hiroshi Agasa, is a middle-aged inventor and a trusted family friend of the Kudo household. He appears in Case Closed: The Fourteenth Target as a supporting figure who helps the young detective Conan Edogawa and his friends. In the film, Agasa is first seen escorting the group of children known as the Detective Boys to the Tohto Aeronautic Memorial Museum, where he tries to entertain them with one of his traditional riddles. Later, while repairing Conan's skateboard at his home, Agasa becomes the victim of an attack when a rock is thrown through his front door and a motorcyclist fires a crossbow at him. This assault places him among the targets in a serial attacker's scheme, with his role in the pattern tied to his name, as the final character of his first name can be read as a combination of the numerals ten and one, corresponding to eleven in the playing-card-themed pattern used by the culprit.

By background, Agasa is a brilliant inventor who lives next door to Shinichi Kudo and was the first person to learn that Conan is actually the shrunken high school detective. He is known for creating a wide range of gadgets, including Conan's power-enhancing kick shoes, stun-gun wristwatch, and voice-changing bowtie, as well as the badges and other equipment used by the Detective Boys. He supports his work through patents and inventions, and his home laboratory serves as a gathering place for the children he looks after. Although many of his creations are playful or prone to failure, his intelligence is genuine, and he has become an indispensable ally in Conan's secret work.

In personality, Agasa is jovial, caring, and outgoing, with a warm and paternal attitude toward the children around him. He enjoys spending time with the Detective Boys, taking them on outings and trips, and he shows consistent concern for their safety. His motivation stems from his loyalty to Conan and his desire to help protect those he cares about, often placing himself in harm's way, as seen when he investigates the attack on his own home. He also has a playful streak, taking pride in his inventions and enjoying simple pleasures such as pasta and tomato juice.

His key relationships include his bond with Conan, whom he assists as a confidant and technical advisor; Ran Mouri, whom he has known since childhood; and the Detective Boys, for whom he acts as a guardian figure. The film also demonstrates how his connection to the central case makes him a meaningful part of the story, as his personal information helps Conan deduce the meaning behind the attacks. Though he does not fight or perform detective work himself, his courage, inventive skill, and dependable nature define his development, showing him as a calm and supportive presence who remains a vital part of the group even when he is the one in danger.