Nazo no Shoujo

The Girl in the Illusionary World is the only human living in the Illusionary World, a world Tomoya dreams of. She creates a body out of garbage for an unnamed entity only referred to as "Me," so that she will not be alone in her world.

Being the only human in the Illusionary world, she can create things out of garbage, such as toys to play with, but cannot infuse life into them, unless they themselves choose to come to such a place.

Living in a gray and sad world with only a garbage robot, she is shown to be a kind and caring girl, who constantly wishes to always be together with her robot, also very lonely and calm. She has the ability to turn junk into machines and robots, which may have the connection to Ushio's fondness in robot toys.

Her identity is major spoiler which is not revealed until the very end. Though never stated, she might have been aware of this all the time.