Eijiro is a muscular young man of average height and a rather impressive physique for his young age. He has red eyes pointed slightly inwards, and a small scar just above his right eye. He also has small eyebrows and pointed teeth. His hair is somewhat long, dyed a bright red, and spiked away from his head at all angles with gel, with two more pronounced tufts spiked on either side of his forehead like little horns. This lofty style takes a full three minutes to set.

During his time in Mustafa Private Middle School, however, his hair was black and left in its natural state: just under shoulder length with some shorter bangs between his eyes. He changed it to his current style shortly after being accepted into U.A. High. His middle school uniform was a short-sleeve, button-up white shirt that was tucked in, black pants, and brown dress shoes.

At U.A., he wears the standard U.A. uniform, but with dark red trainers instead of the usual brown dress shoes.

In his hero costume, Eijiro wears two dark red gear-shaped shoulder pads. A similar colored jagged sash joins the one on his left to the right side of his belt, which has a red "R" set into its center, standing for his hero name: Red Riot. Below this, he wears baggy black pants and a red half cape with a ripped hem. He also sports dark red boots and thick rings around his calves. He leaves his chest bare and wears a wired guard around his face, reaching from just above his hairline to below his jaw, an extra piece going over the bridge of his nose, and some spiked pieces around his mouth that resemble little fangs. Overall, the look slightly resembles that of an Oni.

During the Provisional Hero License Exam Arc, Eijiro's costume later gained black sleeves, which he wears to prevent civilians from being hurt by his Quirk, Hardening, during rescues.

Eight years later after the end of the Final War, Eijiro has grown taller and bulkier. His hair has gotten spikier and a bit longer, extending to his shoulders. He also has two spiky strands sticking up like a horn. His hero costume also remains identical aside from a longer half cape.