The slice-of-life battle narrative is set in a future without World War III or an extraterrestrial invasion—just a regular future set after our current era. Robots are a part of everyday life in this planet, and they contribute to numerous parts of civilization. "Shinki" are 15-centimeter-tall (approximately 6-inch-tall) charming companions designed to help people. They commit themselves to serve their "Masters," armed with brains and emotions. These Shinki may even be outfitted with weapons and armor to engage in combat. These Shinki are known as "Busou Shinki" (literally, "armed divine princesses"). Shinki Ann (Arnval), Aines (Altines), and Lene (Altlene) in especially serve Masato, a high school student. When a new Shinki, the bellicose Strarf, joins them, everything changes.