Shiho Miyano (宮野志保 Miyano Shiho?) is a fictional character in the detective manga and anime Case Closed. Shiho is an ally, of the main protagonist Jimmy Kudo, and an ex-member and fugitive from the malevolent "Black Organization" which she betrayed. Although mentally an adult, her body has reverted back to childhood form due to an experimental poison, APTX 4869, which she developed for the Black Organization and subsequently used on herself in a failed suicide attempt. She often helps Jimmy Kudo with cases while she tries to develop an antidote for the poison she created.
Shiho Miyano grew up within the villainous secret crime syndicate, the "Black Organization," along with her sister, Akemi. She is the daughter of an English mother and a Japanese father, also scientists and members of the Black Organization, both of whom are dead. A prodigy, she was sent to the United States for education at a young age, then returned to Japan as a chemist to continue an unfinished secret project that her parents had been working on for the Black Organization. Her code name within the organization is "Sherry".
Shiho was about 18 years old when she developed the experimental test compound APTX 4869. She discovered that it could be used as a poison to kill without leaving any traces of itself in a body. In the manga, while researching its effects, Shiho noticed that a rare few of her lab mice had become younger after being given the drug instead of dying. Meanwhile, the Black Organization had begun using APTX 4869 to commit untraceable murders. Unaware of the drug's rare side effect, the Black Organization orders a search for Shinichi Kudo because his body had not been found. Shiho searched Shinichi's house twice after he had been shrunk to confirm his death for the Black Organization. She began to suspect Shinichi's transformation after she searched his house for the second time and noticed that his childhood clothes were missing. Shiho then confirmed him as deceased so the organization would not look into the matter further and kill him.
Her dissatisfaction over the Black Organization's usage of the APTX 4869-- for killing purposes, in addition to her open questioning over the murder of her sister Akemi Miyano resulted in her imprisonment and scheduled execution by the Black Organization. With no other way out, she decided to secretly commit suicide by taking a pill of APTX 4869.
However, it made her body's physical age regress to that of about her seven or eight-year-old self, the same fluke that happened to Shinichi Kudo. With her new small body, she escapes from the Black Organization and collapses in front of Shinichi's house, hoping he may be able to help her. She was then found and adopted by Hiroshi Agasa.
To prevent the knowledge of her transfiguration from being discovered, she and Hiroshi Agasa created her alias Ai Haibara (灰原哀, Haibara Ai?). The translated Viz manga had her alias as Anita Hailey from Anna Katherine Green, the first American mystery writer, and Hailey was suggested by Agasa as it means "hero". Though she took the name, she disagreed with the reasoning. She then attends Teitan Elementary along with Conan, and helps him solve cases and find clues about the Black Organization.
Shiho has a jaded, mistrustful, sarcastic, and cold attitude and often reminds others about the darker side of reality and human nature. Anita also acts older than she is supposed to be in school, which the detective boys refer to as "cool". But despite her cold acts, Shiho is actually a kind and caring girl.
In the fourth movie in the series, she says to Jimmy/Conan that she wished that she would forget her memories about the Black Organization, the death of her sister and the pill, claiming all she wants was to be a normal little girl and live together with Conan instead. But then as Conan was shocked by the words, Ai immediately said that she was lying, keeping in line with the sarcastic part of her personality. This could also be interpreted as a sign of insecurity: at times, she says things that may or may not be her actual beliefs. If they're taken badly, she may simply choose to cover them up by saying she's joking. For example, at one point, she tells Conan that her age is "18, perfect for you, right?". Conan is surprised - "Just kidding." If interpreted that way, she may or may not have some affection beyond friendship for Conan/Jimmy; however, which ever the case, she certainly respects him. Ai also seems to have some interest in fashion, as she has made repeated requests for a certain type of purse when asked to do something.
She is fearful of Black Organization members Vermouth, Gin and worries they will find her one day and kill her along with anyone who knows about her. When a Black Organization member is nearby, she can feel their malicious stares. As Ai Haibara, she is very indifferent to the ideals pitched in by the Junior Detective League. Often she acts as a babysitter for them, explaining complicated matters to them or keeping them out of trouble. Still, she regards them all as the first real friends she has ever had.
She has an interesting relationship with Rachel, where it initially appears that she is avoiding her. She frequently ignores Rachel's comments toward her, even going so far as to pretend to be asleep when she enters a room (though it is very transparent to everyone that it's an act). Conan is mystified as to what would make Ai act this way, and no clear motive is actually presented. However, strong clues have shown that Ai is reminded of her sister when sees Rachel, repeatedly shown thinking about her sister during certain moments when Rachel is near. While she maintains her distance from Rachel, she is motivated to speak to her in one case where Rachel leaving Professor Agasa's residence could endanger her life, asking her not to go (though avoiding saying why). Rachel appears to think Ai does not like her for some unknown reason, but she respects Ai's need for distance. She maintains a friendly demeanor toward her, and treats her like the other children.
Shiho was introduced as Anita Hailey, a new student in Conan's classroom. Later, she reveals herself to Conan and reveals the facts about the Black Organization. She then attends the series as a regular cast and joins Conan in his investigation. She has had three run ins with the Black Organization. As the series progress, Anita had developed a temporary antidote to APTX 4869 and continues to tweak it until it becomes complete.