Anti, originally dubbed the Mysterious Boy, is a sentient kaiju engineered by Akane Shinjo solely to annihilate Gridman. Equipped with a replicative ability to adapt from adversaries, he harbored unrelenting hatred for his target, violently dismissing any interference during confrontations. His human guise manifested as a reserved, perpetually hungry teenager with blunt social instincts, frequently grappling with his ambiguous identity as kaiju or human. Despite enduring Akane’s cruelty, he clung to unwavering loyalty, shielding her from a forest fire and avoiding collateral harm unrelated to his mission.

Repeated losses and encounters with Gridman and Calibur sparked introspection, redirecting his fury into a drive to protect. This evolution, amplified by his adaptive prowess, birthed Gridknight—a guardian form mirroring Gridman’s visage. When Akane severed their bond, he embraced autonomy, later confronting her monstrous incarnation to save her, a sacrifice that nearly destroyed him until revival restored his body, including a regenerated eye.

Reemerging as the adult Knight, he allied with Anosillus the 2nd to combat kaiju in a fresh reality. His stoicism persisted, yet he grew fiercely defensive of his partner while deflecting sentimental claims. Teaming with Dynazenon’s pilots, he merged Gridknight with their mecha, creating Kaiser Gridknight—a hybrid entity uniting Dynazenon’s brute force and Goldburn’s shielding.

His journey concluded with gratitude toward Akane, recognizing her as his origin despite their tumultuous past. Once a wrathful weapon, he reshaped himself into an independent hero, navigating themes of self-discovery and atonement. His arsenal grew to include united assaults like the Blazing Hot Inferno alongside Dynazenon and fusion forms such as Rogue Kaiser Gridman during cross-dimensional conflicts.