OVA
Description
After members of the Black Organization forcibly administered the experimental poison APTX 4869 to Shinichi Kudo, his body shrank to that of a six or seven-year-old child while his nervous system, memories, personality, and deductive abilities remained intact. Adopting the alias Conan Edogawa—derived from mystery authors Arthur Conan Doyle and Edogawa Rampo—he sought protection for himself and his loved ones. Neighbor Professor Hiroshi Agasa arranged for Conan to live with childhood friend Ran Mouri and her father, private detective Kogoro Mouri. This placement granted access to Kogoro's cases, enabling Conan to pursue leads on the Black Organization.

Covertly assisting Kogoro, Conan employs Agasa’s inventions: a stun gun wristwatch tranquilizes Kogoro while a voice-changing bowtie simulates his deductions, crafting the "Sleeping Kogoro" persona. Additional gadgets include power-enhancing kick shoes, tracking glasses, and a solar-powered skateboard. To maintain cover, Conan attends Teitan Elementary School, befriending classmates Ayumi Yoshida, Mitsuhiko Tsuburaya, and Genta Kojima. They form the Detective Boys, solving minor cases independently. Conan struggles to mimic childlike behavior, often slipping into advanced reasoning or adult speech during investigations, which he attributes to things "heard on TV" or "taught by Uncle Kogoro, Professor Agasa, or Shinichi-niichan." He addresses Ran as "Ran-neechan" and Kogoro as "Oji-san" or "Occhan." His secret complicates relationships; Ran, unaware of his identity, confides her feelings for Shinichi to Conan, creating tension.

Conan encounters transfer student Ai Haibara, later revealed as Shiho Miyano—the Organization scientist "Sherry" who developed APTX 4869. After shrinking herself to escape, she joins the Detective Boys, providing intel on the Organization and creating temporary antidotes that briefly revert Conan to Shinichi. These antidotes help preserve his cover during critical moments, leading to mutual confessions with Ran. His investigations intersect with Tokyo Metropolitan Police inspectors Juzo Megure, Wataru Takagi, and Miwako Sato, though he typically operates through Kogoro. Allies who suspect his capabilities include FBI agents Jodie Starling and Shuichi Akai, and Nagano Inspector Kansuke Yamato. Together, they combat the Organization, embedding CIA agent Hidemi Hondou ("Kir") as a mole.

Conan confronts high-ranking Organization members like Vermouth, Kir, Bourbon, and Rum—the latter complicated by Haibara’s vague descriptions of Rum as a large man, feminine figure, or old man. His approach to culprits evolves; after failing to prevent an early culprit’s suicide, he adopts the principle that a detective enabling a killer’s death is no better than a murderer. He increasingly intervenes to stop suicides and offers second chances to failed perpetrators driven by misunderstandings.

In the OVA "The Miracle of Excalibur," Conan aids Agasa and a baseball coach in boosting young player Minae’s confidence. They plant a bat in the ground, fabricating a legend that extracting it grants baseball prowess—mirroring King Arthur. Conan discreetly softens the soil around the bat with a modified squirt gun, ensuring Minae can pull it out. He prevents interference from Kogoro, the Detective Boys, or police detectives Takagi and Chiba, tranquilizing Kogoro when he mistakes the bat for his own. Later, he redirects police attention after they confuse the bat with a robbery weapon. This incident underscores Conan’s orchestration of elaborate ruses to help others while preserving his cover.

Conan continues balancing his dual life, pursuing the Organization through cases from the Mouri Detective Agency, the Detective Boys, and his allies, all while safeguarding his identity.