A boy with messy blue hair and blue eyes. He has a kind and altruistic personality. He refers to the Metal Breath he obtained as a symbol of friendship and has never once acted coercively. He calmly tries to persuade Metal Cardbots who cause trouble due to maladjustment on Earth through dialogue until the end, possessing a level of courage and firm values that are hard to believe for an elementary schooler in his early teens. Even after obtaining the Metal Breath, he has never called himself a king or a leader. He is a soul partner who has built a long-standing friendship with Blue Cop.

Calm, thoughtful, gentle, and kind. In contrast to the passionate and quirky Jun, he is the type who has a cool head but a warm heart. He is responsible and values principles and morality. Even before meeting Jun, he showed an intellectual side by independently researching Earth and its indigenous humans, quickly adapting to their social norms and culture. On the other hand, he has a bit of a clumsy streak, often causing accidents or making mistakes unintentionally. He is a soul partner who has built a long-standing friendship with Jun. He feels deep disappointment and regret over the corruption of his former superior and hero, the Star Guardian Wildgard.

Collaborating with Guest. A cunning and arrogant strategist. In the past, he was Blue Cop's superior, a righteous and brave Star Guardian who was awarded the Machina Cross of Merit three times and hailed as a hero. However, he suddenly rebelled against Deus Machina, committed the felony of trespassing into the sanctuary of Planet Machina to steal the Memory Core, and was subsequently expelled from the Star Guardians. His ability to combine was sealed, and he was sentenced to imprisonment deep underground. He shares a relationship of trust and partnership with Guest, the only one who understands his past, and he protects Guest thoroughly. While he acknowledges the growth of Blue Cop, who opposes him, their relationship is poor, as he criticizes Blue Cop as a foolish junior who knows nothing.