Yuma Asahara, a six-year-old classmate of Ashibe, sports spiky black hair, prominent eyebrows, and wide, curious black eyes. He dresses in a red T-shirt marked by two horizontal yellow stripes, paired with dark blue shorts, white socks, and light blue shoes.

Naturally shy, Yuma prefers quiet observation, often lingering on the sidelines while peers buzz with excitement—such as staying seated, absorbed in a book, as classmates eagerly discuss Ashibe’s pet seal, Goma-chan. When prompted about the unusual pet, he hesitates, murmuring a tentative question about its normality.

His reserved demeanor shifts after witnessing Ashibe employ the "Brotherly Love Hold" to settle a dispute. During a walk home with Ashibe and their classmate Mao, Yuma watches intently as Ashibe faces down Sakata and Big Bro, who block their path. Ashibe’s calm use of the hold to defuse the standoff sparks Yuma’s admiration. Wide-eyed, he later asks about the technique, signaling his evolution from a silent spectator to someone actively intrigued by Ashibe’s boldness.