"Back Arrow" is set in the world of Lingalind, a land surrounded by a massive wall that is believed to protect its inhabitants from the outside world. The people of Lingalind worship the wall as divine, believing it to be the source of their prosperity and safety. However, the arrival of a mysterious man named Back Arrow disrupts this belief. Back Arrow claims to have come from beyond the wall, a statement that challenges the fundamental tenets of Lingalind's society. His presence sparks curiosity and conflict, as he possesses a unique Briheight, a mechanized armor powered by the user's convictions.

The story unfolds as Back Arrow allies with the inhabitants of the small border village of Edger Village, including the determined and resourceful Elsha Lean and the pragmatic Bit Namital. Together, they navigate the political and military tensions of Lingalind, which is divided into two rival nations: the militaristic Rekka Empire and the theocratic Lutoh Kingdom. Both nations seek to exploit Back Arrow's knowledge of the outside world and his powerful Briheight for their own agendas. As the conflict escalates, Back Arrow and his allies uncover deeper truths about the wall, the nature of their world, and the origins of Briheights.

The narrative explores themes of belief, identity, and the consequences of challenging established systems. Back Arrow's journey is marked by his unwavering determination to return to his homeland, which drives much of the plot. The series balances action-packed battles involving Briheights with moments of introspection and character development. Key characters include Atlee Ariel, a Rekka Empire pilot with a strong sense of duty; Kai Rhodan, a cunning and ambitious Lutoh operative; and Shu Bi, a mysterious figure with ties to the wall's secrets. As alliances shift and revelations come to light, the story builds toward a climactic confrontation that questions the very foundations of Lingalind's existence.