Kasumi has long light blue colored hair that extends past her shoulders with the hair in front of her forehead is cut diagonally and some that are the side that is cut just above her chin. She also has dark colored triangle shape eyebrows.
Kasumi wears black long sleeved jacket over a light colored button down shirt and a black tie, black pants, black socks, black shoes, and a belt that she uses to hold her sword.
While training, Kasumi has her hair tied in a ponytail and wears a dark colored track suit.
Kasumi is a kind hearted, hard-working girl who isn't as jaded as some of her classmates. She's much more restrained, down to earth, and behaves like a normal girl. Kasumi wants to be a sorcerer to make money and she's a fan of famous sorcerers like Gojo. Despite being ordered to do so by the principal, Kasumi was uncomfortable about her class' attempt on Yuji's life and apologizes for it later.
She constantly refers to herself as useless and genuinely fears that her weakness causes people's for others trying to protect her. Miwa admits to gripping her sword tightly out of fear of dying, however, she is willing to risk her life against a stronger enemy with the right motivation.
Kasumi comes from a poor family and has two younger brothers. She was the captain of the youth basketball team. In Junior High, she met a mentor who would allow her to become a jujutsu sorcerer. Although she had never held a sword before, she trained so that she wouldn't be a burden to her mother.
Kasumi accompanies principal Yoshinobu, as his secretary, to a meeting with principal Masamichi. While Yoshinobu talks with Gojo, as they wait for Masamichi, Kasumi thinks about how cool Gojo is. Kasumi is shocked when Gojo tells them that Masamichi will arrive in 2 hour, as he is leaving. When Yoshinobu tells her to go and get him some tea, Kasumi heads out while hoping to get a picture with Gojo. She is able to get a photo with Gojo but ends up forgetting about the tea.
On the day of the Kyoto Goodwill Event, Kasumi accompanies the Kyoto students and faculty to the Tokyo college. After encountering the Tokyo students, Kasumi is glad of Gojo's arrival and is even given a souvenir from his trip. Afterwards, Kasumi attends a meet with the other Kyoto students and principal Yoshinobu. Yoshinobu tells them to kill Sukuna's host, Yuji, during the event, which Kasumi thinks about how she doesn't want to. After Aoi and Yoshinobu leave, Kasumi talks with the other student one how they should handle the event.
When the event starts, Kasumi and the others manage to locate Yuji and surround him. As Mai draws Yuji to her, Kasumi goes to attack him but Yuji manages to evade her. As Aoi forces the Kyoto students to retreat from killing Yuji, Kasumi is glad about that. As Kasumi retreat with Noritoshi, both of them encounter Megumi and Maki.
As Kasumi takes on Maki, Maki wonders why she separated from Noritoshi. Kasumi tells Maki that she wants to use this event in order to get promoted and help out her family. After talking, Kasumi and Maki continue to fight with neither holding back. As Kasumi fight Maki, she notices that Maki is stronger then what Mai had told her. As Kasumi is put on the defensive by Maki's attacks, she decides to take a stance in order to counter. When Maki breaks her weapon, Miwa wonder why she did that. As Maki throws a part of her broken weapon at Kasumi, Kasumi easily blocks it but notices that Maki had thrown a kunai. As Maki manages to get close to Kasumi, Kasumi defend herself against Maki. Kasumi notices that her feet had moved and plans to get back into position, but Maki tosses Kasumi and even disarms her. Kasumi then asks for her sword back but Maki doesn't give it and leaves.
As Kasumi wonders what to do, she suddenly gets a call from Mechamaru. As she answers the phone, Toge is on the other side and puts her to sleep. When intruders invade the event, Kasumi is still fast asleep.
After the invaders have been dealt with, Kasumi attends a meeting and agrees with the others to continue the event. One the second day of the event, Kasumi plays baseball with the others. After the event is finished, Kasumi heads back to Kyoto along with the students and faculty.
Sometime later, Kasumi informs Mechamaru that their notebooks are due that day. After telling Kasumi where his notebook is and that he will be asleep for a bit, Kasumi pokes Mechamaru and wonders were his real body is at. Later, Kasumi talks with Mechamaru and informs him that she wishes to get closer to him along with meeting with him in person one day.
Miwa is given privacy on the train to Shibuya as she holds onto the last device that Kokichi is talking through. He tries to convince her that the battle will end soon and she should turn back. Miwa asks Kokichi why it's only Todo and Arata where Kokichi explains that there's a 99% chance that Todo would survive and that Arata's cursed technique is useful. Miwa suddenly tearfully yells and asks if she was so weak that he needed to act in secrecy and ensure they wouldn't be available on 31st, only for Kokichi refute and say he was truly weak for making these mistakes. While he's in the middle of talking, tears suddenly sprout from Miwa's eyes as she hugs the device. When Kokichi tells Miwa that it's time to say goodbye, Miwa tearfully begs for him to not leave. Kokichi then tells Miwa that he did truly love her and asks for her to find her happiness, no matter how she does it, as long as she's happy his wish will become true. She then starts crying tearfully in the train.
When the Kyoto team ambush Geto, Miwa manages to get behind him and unleashes New Shadow Style: Batto Sword Drawing. Even though she puts everything she had into the attack, Geto effortlessly destroys her sword with his bare hands and uses Maximum Uzumaki at point blank range. Miwa is protect by Momo, Utahime and Kusakabe who Miwa recognizes. She and the others are later frozen in place by Uraume's Frost Calm attack.
Abilities and Powers
Overall Skill Level: Kasumi is a grade 3 sorcerer capable of using the New Shadow Style swordsmanship techniques. Her lack of an Innate Technique makes it difficult to stand up to some her fellow jujutsu students, and she was completely overpowered by Maki, someone with advanced levels of physical prowess.
Expert Swordsman: Kasumi wields a katana as her main weapon in battle. She has studied Iai sword drawing techniques and is capable of incorporating jujutsu into her swordsmanship.
- Kasumi's surname contains the kanji for "three" (三 mi?) and "ring, loop" (輪 wa?), and her first name contains "mist" (輪 kasumi?).
- Kasumi ranked 11th place in the manga's 1st Character Popularity Poll with 4,923 votes.
- During the omake at the end of episode 15 of the anime, characters are asked to answer the question "What's your type?". When it comes Miwa's turn, she blushingly answers with "An average good looking guy, but the important thing is that he be a person I have fun being around and someone who I think is the only one for me".