Hikaru’s ordinary school life takes a dramatic turn when he encounters Alma, an alien entity resembling a mechanical limb called Mecha-Ude. Alma, a member of an alien species, is on the run from a sinister group hunting down her kind in search of someone with unparalleled power. Tasked with the resistance group ARMS, this unlikely duo will embark on a dangerous journey to rescue Mecha-Ude.