On December 24, 2009 , android boy Seiru Kamioka was spending a happy Christmas with his mother, Ruriko Kamioka , and their animaroid, Kiddy . However, their happy moment was suddenly shattered by the arrival of the Knockers group " Pendragon ," led by Takeru Kirishima. Ruriko was torn to pieces and kidnapped by Takeru's Knockers ability, putting Seiru in danger as he tries to rescue her. But Kiddy boosts Seiru, transforming him into combat mode and allowing him to repel the Knockers who were ordered to clean up the mess.

Seiryu and Kiddy continue their arduous journey, encountering and parting ways with various characters along the way, in order to reclaim their mother...