In the realm of Lingalind, a sacred barrier encloses the world, bestowing monthly celestial gifts known as 'Rakuho' upon the land. These gifts, in the form of metallic armbands, grant the power to transform into mighty mechanical beings called 'Briheights.' As nations vie for supremacy through these gifts, Lingalind is caught in a perpetual state of conflict. However, everything changes when a Rakuho capsule falls from the sky, carrying an enigmatic black-haired man named 'Back Arrow' who claims to originate from beyond the impenetrable wall. With this revelation, the foundations of Lingalind's beliefs are shaken, setting the stage for a potentially transformative upheaval.