Sumi has light skin and a set of black, button-like eyes. She wears her hair in low twintails fastened with blue butterfly clips.
She sports a long-sleeved nurse uniform tied with a blue ribbon around her waist and wears white socks and shoes.
Like the other members of the trio, she is very bright cheery and helpful.
At the Butterfly Mansion, after an injured man (whom is a Demon Slayer) shatters a glass within his room, she was so frightened that ended up hugging each other and shaking with Naho Takada. The man, whom recently lost a portion below the elbow of one of his arms, was stopped by Genya Shinazugawa before he could throw a vase to the girls within the Mansion. After Genya calms down the man, the latter cry apologizing for the loss of his comrade. This makes Sumi and Naho to cry as well, so Genya decides to come back to sleep in his room.
Later on Sumi carries out Genya's medicine being worry about him. After he wakes up, Sumi expresses that she heard him apologizing to his brother while he was asleep. She tanks him for protecting them back then. When Genya asks about the injured man, she replies that he is now quiet and will be sent to a hospital next day. She states that Aoi and Naho came over to thank him but he was asleep.
She asks if the Wind Hashira is his older brother. She clarifies that is because of their names and appearance that she believes this. However, she thinks that his older brother seems very scary. Without thinking, Genya protests loudly against this statement. He says that his older brother is really very kind and reliable. Seeing that Sumi's eyes full of compassion, he proceeds to share his story with her, about his family and how he regrets misunderstanding his older brother.
Sumi tells him to not worry about his mistake and that as long as both are still alive, there's always a chance to start over. After hearing her encouragement, he reflects on his past actions ending up apologizing once more. After Sumi tells him to not say sorry, Tanjiro Kamado wakes up and tells him in a good tone to be grateful. Genya, whom was embarrassed, proceeds to pull Tanjiro's cheeks asking if he was awake the whole time. After Tanjiro clears his doubts, Sumi asks Genya to not being aggressive with the injured Tanjiro. After Genya thanks her, she shows him a smile.
After going out of Genya's room, she meets Aoi. She tells her how Tanjiro and Genya are doing. She was happy thinking about how kind Genya ended up and wasn't as scary as she once thought. She thinks to herself of telling this to Naho and Kiyo. They talked about the visit of the Wind Hashira to the Butterfly Mansion this morning. Aoi gives her instructions on how to take care of Tanjiro. After Aoi walks off, she thinks that Sanemi really came over to see if Genya was alright.
She goes to feed a shy Genya alongside Aoi. After Tanjiro states that Genya is getting along with everyone, much to the latter's dismay.
She is shown alongside Aoi Kanzaki, Kiyo Terauchi and Naho Takada taking care of Nezuko Kamado under the sun around the Butterfly Mansion. After Zenitsu, who came first screaming of joy of seeing Nezuko under the sun, goes threatening to spitroast Inosuke, she hides behind Nezuko showing some concern.
Abilities and Powers
Though she has never displayed or, in the case of Aoi, alluded to any special abilities, they are the ones who taught the Total Concentration: Constant (
- Sumi's chosen name contains the characters for "middle" (中 naka?) and "meadow" (原 hara?).
- She shares the same name as Sumi Shinazugawa, Genya Shinazugawa and Sanemi Shinazugawa's younger sister.
- (To Genya Shinazugawa) "As long as you’re still alive, there’s always a chance that the two of you can start over. You must make up with your brother."