Shujaku no Rei, also called Suzaku no Rey, holds the position of the Crimson Phoenix of the South, one of the Six Saint Beasts chosen by Zeus to govern Earth's animals, embodying the essence of summer. His striking appearance features long purple hair, pale skin, and a distinctive red tiara. He wears a sleeveless red qipao-like robe with white linings, paired with black pants and boots.

Rei exhibits a deeply gentle and nurturing nature, expressed through exceptional culinary talent and a profound affinity for birds, particularly chickens. This connection leads him to avoid eating poultry, viewing it as cannibalism. He frequently finds himself the target of pranks orchestrated by fellow Saint Beast Gai, though these attempts usually fail.

Zeus bestowed the Spear of Suzaku upon Rei, symbolizing his role, along with the ability to manifest red-gold wings for flight upon reaching adulthood. During missions on Earth, Rei confronts controlled guardian angels like Hayabusa no Hiro, wielding his spear in combat.

Significant relationships shape Rei's path. He shares an intimate, protective bond built on mutual trust with Houou no Luca. Rei is one of only two individuals aware of the seal on Luca's forehead. During a mission, Rei discovered a knife bearing an identical mark and safeguarded it; this knife later proved crucial in unlocking Luca's sealed memories of being Zeus's son. Rei maintains respect for Judas as the Saint Beasts' leader, who shields him in conflict. A childhood friendship with Shin endures into adulthood, and he regards Goh with esteem as an older brother figure. Rei also forged a close friendship with Maya, the half-human angel.

Rei's background is interwoven with key events in the Saint Beast saga. He participated in the initial rebellion against Zeus's tyranny alongside Judas, Luca, and the others. After the coup failed, Rei and three comrades were manipulated by Zeus's forces into turning against Judas and Luca. In the final confrontation, Rei fought alongside the corrupted Saint Beasts until Shin's last-moment realization halted their attack. Following Judas and Luca's banishment to hell, Rei remained in Heaven under Zeus's control, harboring unresolved resentment towards his former allies.

Rei actively aided Luca in recovering his sealed memories by presenting the knife matching Luca's forehead mark. He joined missions to Earth, including sealing the Land of Revival with Goh and later helping rescue Judas from Zeus's torture. During the frozen castle incident, Rei assisted in freeing Luca, Gou, Gai, and Kira from imprisonment.