Nanato Mukaido, chosen by the angel Baret as a candidate for Godhood, previously worked as a product planner and designer for an apparel company. A married man with one daughter and another child expected, he faced a terminal cancer diagnosis roughly four months before the Jinbo Stadium events, receiving a prognosis of three months to live. When Baret appeared approximately three months later offering god candidacy, Mukaido accepted primarily to remain with his family.

Fearing for his family's financial future after his death, he utilized Red Arrows—angelic tools inducing profound love and obedience for 33 days—to manipulate wealthy individuals, securing 200 million yen in cash. At Jinbo Stadium during Metropoliman's orchestrated meeting, he deployed fourteen detectives and psychologists, each under Red Arrow influence, to identify fellow God candidates. This operation located Mirai Kakehashi, Saki Hanakago, and an unidentified young boy.

Tracking Mirai and Saki to Saki's residence after the stadium, Mukaido overheard their angels discuss forming an alliance. He revealed himself and proposed teaming up. To demonstrate trustworthiness, he invited them to shoot him with a Red Arrow, assuring sincere intent to collaborate against Metropoliman. As part of this alliance, he later procured firearms from the Japan Self-Defense Forces to bolster their capabilities against Metropoliman, with Mirai insisting he maintain his cancer treatments as a partnership condition.

Physically, Mukaido sported stubble, a trimmed beard, and messy dark hair. He typically dressed formally in a light-colored dress shirt, necktie, black pants, and dress shoes. In combat, he adopted the alias "Green," wearing a heavy militaristic green costume and matching helmet.

His abilities included Wings granting flight and Red Arrows enforcing temporary, absolute loyalty through induced affection. The arrows' effect was not mind control but genuine, overwhelming devotion compelling targets to fulfill the user's wishes.