Yuru, a young hunter, lives in a small village deep in the mountains, hunting wild game and leading a humble life with Asa, his younger twin sister. Their peaceful lives are torn apart when a dragon’s roar echoes across the sky. What secrets lurk within their village? What fate awaits them?

Hikaru’s ordinary middle school life takes a thrilling turn when he encounters Alma, an alien entity resembling a mechanized limb called Mecha-Ude. Alma, a member of a rare species, is fleeing from a sinister group hunting their kind down in search of one possessing unparalleled power. Tasked by the resistance group ARMS, this unlikely duo will embark on a perilous journey to save the Mecha-Ude.