Sumihiko is a young man with short, ruffled black hair with burgundy tips, that he wears combed back, a few stray tufts falling down over his forehead. He has wide, dark red eyes with white pupils that appear lighter around the lower section of his irises. Overall, his appearance bears a strong resemblance to that of his ancestor Tanjiro Kamado.
Sumihiko wears his high school's uniform, consisting of a pale blue dress shirt with a sleeveless, white v-neck cardigan worn over the top, and plain black pants. He wears a black necktie around his neck, as well as a pair of dark brown dress shoes.
Sumihiko takes after Tanjiro in terms of personality as well as appearance, as he too is kind and cheerful by nature, smiling and talking happily to his friend Tojuro as they run together. He also appears to be rather sleepy, not waking up when Kanata tried to get him up for school and implying he's slept in and been late numerous times, as well as being shown to be yawning on the cover page. He appears to be rather athletic, countering his brother's noted skill in more academic subjects, as he was seen jumping down and off tall buildings and swinging himself from stairwells and railings on his run to school.
Despite being somewhat clumsy, Sumihiko has respect for others, as, when he runs past a pair of older men who resemble Sakonji Urokodaki and Jigoro Kuwajima playing shogi and a group of young girls who look like Naho Takada, Sumi Nakahara and Kiyo Terauchi, he turns back with an apologetic expression and says he's sorry for any disruption he's caused.
As Sumihiko's brother, Kanata, gets ready to leave for school, he tells a dozing Sumihiko to wake up for the 28th time, to which Sumihiko replies that he is up as Kanata leaves the house without him.
Sometime later, Sumihiko wakes up, realizing he's late and asking himself why nobody woke him up. After getting dressed, Sumihiko leaves the apartment through his nine-storey-up bedroom window, calling out to his mother that he's leaving to as he jumps down onto the balcony below and swings himself onto the roof of the neighbouring building. He crosses the roof as he remarks to himself that he wants the perfect attendance award, and then climbs down the other side of the building via the stairwells and lands on the ground.
Sumihiko runs past a pair of old men sitting and playing shogi in a traditional Japanese-style house, the doors open, and the shorter Jigoro-lookalike man asks what's with him every morning. Sumihiko apologizes to them as the man mutters that he's a hooligan, and continues to run down the street, passing three young girls who laugh and exclaim that he's the "running man." Embarrassed, he blushes at the nickname as he passes a police patrol car manned by two officers who bear a resemblance to the Shinazugawa brothers. Sumihiko flips himself over the hood of the car, muttering an apology to the officers, then sprints past a group of kids who look like Giyu Tomioka, Sabito and Makomo who are exchanging kitsune mask-like collectible toys.
Now close to the school's entrance, Sumihiko's friend Tojuro, who looks similar to Kyojuro Rengoku, catches up with him and they run together towards the school. After they greet each other, Sumihiko remarks that it's unusual for Tojuro to be late, to which the latter responds that he got caught up training until 4 A.M. and was unable to hear anything until his father whacked him. The two policemen from earlier approach the pair in their patrol car, asking them to stop, but Tojuro ignores them and continues the conversation, telling Sumihiko that he should join a sports club at school. Sumihiko replies that it'd cut into his sleep, and Tojuro laughs and says that he should at least try something because he'd be awesome at it. Sumihiko says he could never hold a candle to Tojuro in terms of sport, as the officers continue to shout at the pair to stop.
A teacher who resembles Murata shouts to close the school gate despite it being three minutes too early in an attempt to stop Sumihiko's offences, but the two just hoist themselves over the gate, smiling at each other that they're glad to have made it to school in time.
Abilities and Powers
As a regular human, Sumihiko hasn't been shown to possess any form of unnatural power. He is, however, shown to possess a degree of skill in athletics, acrobatics, and parkour, along with a prodigious physical condition. His skills allow him to easily jump from building to building, descend multiple floors by climbing down them with careful maneuvers, perform acrobatic movements to pass through a moving police car, and easily jump over his school's closing gate.