AKA Ai Haibara (灰原 哀 Haibara Ai), real name Shiho Miyano (宮野 志保 Miyano Shiho), is the creator of APTX 4869, the pill that shrunk Shinichi Kudo into Conan Edogawa, and a victim of it herself. Formerly Sherry (シェリー Sherī) of the Black Organization, she is on the run from them and lives with Professor Agasa. She is also one of the few characters who know that Shinichi is Conan.
Shiho Miyano and her older sister, Akemi Miyano, were born into the secret crime syndicate "The Black Organization". Her English mother, Elena Miyano, and her Japanese father, Atsushi Miyano, were both scientists working for the Black Organization on a secret project. While Haibara was young, both her parents died in what was claimed to be an accident. While Akemi lived a normal life, the highly intelligent Shiho was groomed to take over her parents' research. She was sent to the United States for education at a very young age, and then later came back to Japan to finish her parents' secret project, "Silver Bullet". By the age of thirteen she was working as a scientist for the Black Organization, where she was given the codename "Sherry", after the alcoholic drink.
Shiho was about 18 years old when she developed the experimental test compound APTX 4869. While researching its effects, she discovered that it could be used as a poison to kill without leaving any traces of itself in a body. She then noticed that one of her lab mice had become smaller instead of dying, though she did not report that effect. Meanwhile, the Black Organization started human trials, using APTX 4869 to commit untraceable murders. Unaware of the drug's rare side effect when they used it on Shinichi Kudo, the Black Organization ordered a search for him because his body had not been found. Shiho and her team searched Shinichi's house twice to confirm his death, however it lead her to suspect Shinichi had shrunk instead. However, Shiho confirmed him as deceased so the organization would not look into the matter further and kill him after all.
Shiho was unhappy that the Black Organization was using the incomplete APTX 4869 for murder, as she believed that was not the drug's intended purpose. When Shiho learned of Akemi's death, but was given no explanation, she decided to boycott her research until the Black Organization gave her an explanation. Instead, the Organization confined her in a small room to await her execution. With no other way out, she took APTX 4869 intending to commit suicide, but instead shrank. In her new, smaller body, she escaped and attempted to reach Shinichi's house. There she collapsed and was found by Professor Agasa, who eventually adopted her. As it turned out later, Agasa was acquaintances with her parents—especially her father—even though he didn't know at that time that they had children or were part of the Black Organization.
To prevent the knowledge of her transfiguration from being discovered, Shiho and Professor Agasa create her alias Ai Haibara. As Ai Haibara, she attends Teitan Elementary School with Shinichi Kudo's shrunken form, Conan Edogawa. Following her first adventure with the Detective Boys, she reveals her true identity as the developer of APTX 4869 to Conan, and also accurately deduces Conan as Shinichi in the shrunken form, though her deduction is based on prior knowledge of her research and investigation of Shinichi Kudo. Conan protests her presence, but as time passes, he accepts her as a friend, though her cynicism and secretive air still rail him at times. Although she does not think too highly of the Detective Boys' immature antics, she has come to value them all as close friends.
Haibara has begun working on an antidote for the APTX 4869, but since most of the important data had been stored on computer files, which are now mostly destroyed, the work progresses slowly. Conan also eventually succeeds in persuading Vermouth to leave Haibara in peace after ruining a murderous plot. This fragile peace lasts until Sherry's whereabouts leak to the rest of the Black Organization and a second murder plot occurs aboard a train. A counter plan results in an explosion that preserves Shiho's secret identity. Currently all major Black Organization members besides Vermouth believe Sherry is dead.