Yūta Miura operates as a B-rank Attacker in Border's Katori Squad. He has a lean build, light skin, and short, spiky dark brown hair. Off-duty, he favors a hoodie displaying Border's logo on each sleeve over a white round-neck tee and blue jeans. His standard Border uniform features a high-necked black undershirt beneath a purple jacket with long sleeves ending in gloves marked by single black dots on each knuckle. The uniform includes black shoulder pads, white lining, short hip straps, three vertical red lines descending from the collar, and silver ornamental buttons arranged on the chest, sleeves, and hips, paired with purple trousers merging into boots featuring black soles.

Miura maintains a soft-spoken and conflict-averse nature. He frequently attempts to mediate disputes between teammates Yōko Katori and Rokurō Wakamura, though these efforts usually fail. He avoids taking sides and often keeps observations about his teammates to himself unless he believes sharing is beneficial. His attraction to Katori leads him to consistently agree with her statements. His sociable and relaxed demeanor enables positive interactions with younger Attackers.

Serving as the supporting Attacker for Katori Squad, Miura wields a standard white Trigger without specified weapon preferences. During squad operations, his tactical awareness emerges, such as acknowledging opponents' strengths and urging adaptive strategies. He champions creative battle planning, directly encouraging Katori to adopt innovative approaches like Tamakoma's to secure victories, emphasizing their squad's comparable potential.

Characteristic quotes showcase his mediating attempts ("Now, now" to de-escalate arguments), support for Katori ("You're right, Yōko! I agree!"), appeals for squad cohesion ("Our team's in the worst mood ever... Please say something..."), constructive feedback ("I think the reason you're mad at Tamakoma is that you're jealous of them"), and proactive encouragement ("Let's try harder! Even just a little!").

Supplementary details note his preferences for peace, mandarins, tsukemen noodles, and seeing Katori in a good mood. The author compares him to Tatsuya Kuruma, noting Miura lacks Kuruma's wealth. Kazuaki Ōji nicknames him "Muller", potentially derived from the German surname "Müller". His catchphrase "Now, now" peaked at 46 repetitions in a single day.