Shiho Miyano was born into a criminal organization that forced her to work as a scientist from a young age. After her older sister, Akemi Miyano, is murdered, Shiho refuses to cooperate with the organization any longer and tries to kill herself. Instead of dying, she ends up de-aging and escapes the organization. She is taken in by Professor Agasa and works alongside him and Shinichi Kudo (who also shrunk and uses the alias Conan Edogawa) with the goal of taking down the organization and creating a cure to permanently return them to their teenage forms. Shiho also possesses the ability to sense the presence of any nearby organization members.
