Ryu Soma's grandfather developed "Alcoroids," robots that can be used for many purposes. Although Ryu has no interest in developing new models, she loves repairing Alcoroids and treats them as if they were living things. One day, a pretty blonde girl comes to talk to her about "Spirits," Alcoroids with souls. Apparently, Ryu's grandfather left her a locked security box which may have some information on how to find Spirits. Now Ryu is searching for Spirits, though she may be a bit too naive in trusting the blonde girl's motives in doing the same. Are there still Spirits around? Could that strange boy that shows up to save Ryu from time to time possibly be one of them?