Retsu Akagi commands the KiraDeco 5, a human team summoned from Earth to Jewel Land. Hailing from Gunma Prefecture, this junior high schooler fights alongside his younger brother, Midori Akagi. Retsu radiates a hot-blooded, intensely optimistic personality defined by unwavering courage and confidence. He enforces a rigorous self-training routine and constantly rallies his group with an ultra-positive mindset. His enthusiasm erupts in loud declarations of justice and attacks punctuated by the word "BURNING". This single-minded focus blinds him to Midori’s simmering resentment, fueled by Retsu’s overbearing behavior and their troubled history. He dismisses Midori as incapable, overlooking his brother’s intelligence and independent skills, deepening Midori’s jealousy and inferiority complex.

A childhood incident where Retsu lost Midori on Mount Akagi haunts him. Though responsible, Retsu clings to his self-image as justice incarnate, refusing to accept fault—a recurring flaw. His leadership and personality grate on teammates and Jewelpets, yet his fiery passion wins admiration from others. Operating as "Burning Red", he lives in a Jewel Land tree house. Retsu relies solely on exceptional fist-fighting prowess, not magic. His signature attire combines a red leather jacket, black sleeveless shirt, green army trousers, and rugged mountain boots. While highly resistant to dark magic, defenses crumble when psychological vulnerabilities about Midori surface.

His journey forces a confrontation with past failure. Villain Kaiser weaponizes Retsu’s unresolved guilt over abandoning Midori, tricking him into believing Midori’s hatred is absolute. This triggers temporary corruption: Retsu dons an evil costume and sides with antagonists. Angela’s intervention sparks redemption. Retsu admits fault for the Mount Akagi incident and apologizes to Midori, mending their bond.

In the climax, Retsu’s emotional connection with Angela crystallizes into his Jewel of Fate, the Red Angelite. This transformation unlocks enhanced abilities and a new form. Post-mission, he returns to the human world with Midori, wielding his powers against lingering evil. A crane motif, echoing his Gunma roots, symbolizes his character arc.