Suma is a young woman of short height possessing a curvaceous build and shoulder-length black hair with short bangs over her forehead and round, sapphire blue eyes framed with short eyelashes and thin, upturned eyebrows, giving her a friendly and jovial appearance.
Suma wears a short, black (blue in the anime), sleeveless dress with a plunging neckline that exposes her cleavage, which is secured with light-colored obi (gray in the anime) where she probably stores her kunai . She wears gray ankle-length tabi socks and white zōri with blue straps.
Suma's personality is particularly similar to Zenitsu Agatsuma's, expressing overdramatic and exaggerated emotions in practically every situation she's in along with giving off a fearful and unconfident attitude when it comes to dangerous situations, as well as the tendency to cry which is seen when she bursted into tears whenever the Obi Demon launches its attacks in fury, or when after Tengen Uzui praised her, clutching on the latter's uniform while she cries.
At some point of her life, Suma married Tengen Uzui, along with Makio and Hinatsuru. After she left the clan, her family journeyed to see Kagaya Ubuyashiki in order to fight as a part of the Demon Slayer Corps.
At some point in the past, Suma was instructed alongside Makio and Hinatsuru by Tengen on his personal ideology: to put their own lives first, then respectable humans, and lastly himself. Later, when Makio questioned this in private, as it went against what they had been taught as kunoichi. Hinatsuru assured her that as long as she was okay with it, Tengen would also approve of it. She also wished for the four of them to retreat from the front lines as soon as they defeated an Upper Rank.
When investigating the Entertainment District, Suma was assigned as an oiran to the Tokito House. However during the investigation, she disappeared and lost contact with Tengen Uzui. When Tanjiro arrives at the Tokito house in disguise, he overhears the rumor that Suma had run off with a wealthy suitor according to her diary, but is immediately doubtful sensing that something more sinister is occurring.
Later on in the arc, Inosuke Hashibira begins to search for the demon and stumbles upon a cavern with a hanging obi holding multiple people captive. As he begins his assault, he manages to free multiple captives including Suma and Makio. The two women proceed to defend the freed captives from being reabsorbed while Inosuke fights the obi. A large thundering sound is heard coming from above the cave, and Tengen bursts through the ceiling, effectively slashing large portions of the obi. He lets the two women know that he's proud of them causing them both to emotionally tear up.
Suma alerts Tengen and Shinjuro Rengoku that Nezuko Kamado escaped from the Ubayashiki residence and broke down a door.
Overall Abilities: Suma does not possess any form of superhuman abilities. However, as she was raised as a kunoichi, Suma possesses some form of shinobi skills, being capable of wielding a kunai as well as performing maneuvers and fighting much more proficiently than regular people can.
- Suma's name is composed of the kanji for "ought, by all means" (須 su?) and "grind, polish" (磨 ma?).
- According to the second fanbook, Suma is bisexual.
- According to the second fanbook, Suma's sister was actually Tengen's original promised wife, however, Suma wanted to be Tengen's wife instead. Her feelings made her crash the marriage interview to be married to Tengen.
- Hinatsuru and Makio were personal additions both Tengen and Suma were happy to welcome.