Kamishiro Rui is a 23-year-old mechanical genius. He is a tall man with pale, dull skin due to eternal stay in the workshop, purple hair with blue strands, amber "cat" eyes. He is filled with a crazy idea — to create a perfect doll that will be completely human-like and will literally do anything for this. Rui also earns money by repairing other people's complex mechanisms and selling his useless ideas. Outwardly, he is extremely gentle and smiling. In fact, he is a cold and cruel man.