The realm of Lingalind is encircled by a mysterious wall, with nothing visible beyond it. The wall, revered as the mother of the land, distributes celestial gift capsules known as "Rakuho" to locations across the continent once a month, containing metallic armbands that allow the wearer to transform into a mechanical being known as a "Briheight." As a result, Lingalind is constantly thrown into chaos by its warring nations, all hoping to strengthen their military prowess by obtaining the offerings for themselves. When a Rakuho crashes into the countryside with an unexpected inhabitant—a mysterious black-haired man—all eyes are on this strange newcomer, who calls himself "Back Arrow," when he claims to have hailed from a place beyond the wall—a place where he claims to have hailed from a place where he claims to have hailed from a place where he claims to have hailed from a place where he claims to have hailed from a