Miho is an extremely popular idol singer and rock star. After viewing one of her concert videos, Key decides that she wants to be like Miho. Miho becomes Key's role model, with Key hoping if she can muster tens of thousands of fans like Miho, then surely Key will become human. Miho was scouted into showbusiness by Tamari, then commissioned to Production Minos. Ajou uses her in his experiments, and the "Miho" seen on stage is actually a humanoid PPOR robot controlled by Miho from a distance. This process is extremely strenuous on Miho's health.
(source: Wikipedia)