Sunred anchors all media as the central protagonist. Approximately 27 years old, he retains an athletic build despite a lifestyle heavy with smoking, drinking, gambling, and minimal non-combat exercise. His Japanese heritage is noted, with both parents deceased and no further family background. He permanently wears a distinctive red helmet featuring a yellow sun logo and green visor; its integrated toxin filter allows him to eat, drink, and smoke without removal. He possesses a full spandex-like battlesuit but rarely wears it, preferring casual, weather-appropriate clothing like t-shirts and shorts during confrontations.

His personality is marked by extreme irritability, impatience, selfishness, and frequent verbal abuse, especially toward Florsheim members. He lives in his girlfriend Kayoko Uchida's apartment, financially dependent on her while contributing minimally. Despite this, he occasionally shows tenderness toward her and enthusiasm for challenging fights. A deep disillusionment stemming from his declining superhero career fuels envy toward colleagues and bitterness over his lack of marketable skills or societal respect. Sentai heroes occupy a low fame tier, below faded pop stars but above obscure athletes, with no government support or benefits like health insurance.

His background includes membership in the disbanded superhero team Kishō Sentai Weather Three; internal conflicts over artistic differences and romantic entanglements caused the split. Former teammates Weather Blue and Weather Yellow now work as a host club host and construction worker, respectively. Sunred maintains contact with them and belongs to a loose nationwide network of regional heroes, including Kyōdai Senshi Abashirin (Hokkaido) and Shinrin Sentai Gurīnrenjā (Aomori). As a senior member, he mentors junior heroes like Tottori Senshi Sakyūn and Naitoman (later Naitōru), though his guidance is often perfunctory.

His abilities encompass superhuman strength and durability, enabling effortless victories over Florsheim monsters. Combat proficiency includes kicks, punches, and puroresu-style wrestling holds, alongside flame-based special moves (only depicted in opening sequences). His helmet grants telescopic vision ("Red Eye"), enhanced hearing ("Red Ear"), and immunity to inhaled toxins/allergens (though not viruses). He possesses mechanical aptitude for improvised repairs despite no formal training. The helmet's filter and his powers function regardless of wearing his battlesuit, which includes a theoretical "Firebird Form" power-up never utilized.

Relationships define much of his existence. His codependency with Kayoko involves frequent arguments, though their relationship persists partly through her friendship with General Vamp. The dynamic with Vamp's Florsheim organization anchors the story; despite subjecting them to physical and psychological abuse, Sunred maintains a stable rivalry. Florsheim's world domination attempts are persistently thwarted, yet interactions extend beyond combat to include receiving homemade food or moving assistance from monsters. This paradox underscores their entrenched roles: Florsheim adheres to evil organization conventions, while Sunred fulfills hero duties with consistent disdain.

Financial struggles recur, necessitating the sale of his crimefighting motorcycle and reliance on Kayoko's income or pachinko winnings. His lack of career progression or adaptation to civilian life remains unchanged across all seasons and manga volumes, with no substantive character development depicted. The narrative explores the mundanity and absurdity of his stagnant existence against Florsheim's equally unchanging ambitions.