A 14 years old girl Hikari Tokawa, receive from her mother, a great scientist, a present. It's a robot. 5 years ago, Hikari's younger sister was killed in an accident - The robot is just like Haruka, it can behave like a human being, but don't have experience in thinking matters. Hikari's angry. However, she notices the photograph of her young sister.—DramaWiki