Ai's Story
Haibara Ai first entered the story as a mysterious new student in Conan's class. She was obviously "interested" in Conan, and at the end of the story, she reveals that she knows Conan's true identity.
Later, at Agasa-hakase's house, Conan learns that Ai used to be a researcher for the Black Organization, but she stopped when her sister was murdered. Since they were going to kill her too, she thought she might as well kill herself by taking the poison that she invented--APTX-4869, the very drug that turned Shinichi into Conan! The drug had the same effect on her, and her hand was small enough to slip through the handcuff. Now Ai is on the run from the Organization, and she resides in Agasa-hakase's house, working on an antidote for the APTX.

About Ai
Ai is a difficult character to describe. She is very quite and introverted, and she seems to have a streak of depression. It is obvious that she hates her former self and wants to forget her past, so perhaps she is happier, being small and able to re-live life?
She is very intelligent and often helps Conan with cases. She also seems to have a crush on Conan...^_~

Friends & Family
Ai currently has NO family. The day she turned small, she went looking for Kudo Shinichi, but collapsed in front of his house. Agasa-hakase found her and took her in out of his kindness.
Ai's older self, Miyano Shiho, had a sister named Miyano Akemi. However, Akemi was killed by the Black Organization, like the rest of their family.