The action of the series takes place in the not-too-distant future, where robots performing a wide variety of functions have long become part of everyday life. Among the many models are "Shinki"—fifteen‑centimeter, eye‑pleasing android assistants (usually in the form of girls), possessing intelligence and emotions and utterly devoted to their owners. Moreover, one can equip Shinki with various weapons and armor and, for example, make them fight each other. The series will revolve around the Shinki Arnvall, Altines, and Altrayn, who serve high‑school senior Masato. The action begins with the addition of the fierce Staarf to their group.