Tokiko Mima, called Key
, is a robot. Since she was created by her 'grandfather', Dr. Mima, she has lived among humans. Now Dr. Mima is dead, and has left behind a cryptic last message: if Key
can somehow get 30,000 people to feel for her, she can become fully human. However, Key
's quest may not be so simple - for an ominous plot is being hatched by Dr. Mima's rival, Jinsaku Ajo.
has created a robot daughter named Key
, but after raising her for a very short time, Mima dies, leaving behind cryptic messages telling Key
how she can become human. Key
must struggle alone to learn the harsh lessons of life and search for the 'key' to her own dream: the power of 30,000 friends to make her a real human girl.