Miu Saionji is the daughter of Miyu Kozuki and Kanata Saionji (Daa! Daa! Daa!). Miu gets sucked into a black hole and is transported to planet Otto. There, she meets Ruu. If you read Daa! Daa! Daa! then you would know that Ruu was the little baby that Miyu and Kanata once took care of.
