Misumi has spiky black hair and wears a pair of glasses, and seems to be slightly smaller sized than the rest of the girls. She wears the white dress worn by the White Knights, along with thigh-high black socks and brown shoes, although she was seen in her old black uniform in a flashback. Under her skirt, Misumi wears white panties with a little yellow ribbon centered below the waistband which can be seen in some scenes. Misumi is noticably shorter than her peers at around 4' 11".
Misumi is first seen in Episode 1 in the chapel with the other White Knights. She is not seen for the rest of the episode.
In Episode 2, Misumi is seen in a flashback standing with Rin, watching with surprise as Miyu Shiratori outperforms Rin in the exam. She is later seen in the chapel, unconscious, with her body draped over a couch, her skirt flipped over her hips to expose her panties and buttocks. An Alien Tendril is seen attached to her just above her buttocks.
Later, as Karen Minamino explores the school and finds the hidden entrance to the basement, Misumi attacks her, descending on her with a kick. Misumi then punches Karen through a door and knocks her glasses askew, crushing them under her foot. She then attempts to heel kick Karen, but is stopped by Risako Nagisa, who grabs her leg and throws her. However, she manages to right herself in the air and lands unharmed on a sofa, to which Risako reacts with shock. Misumi then rises and presumably attacks.
Unfortunately for her, Risako manages to shoot her and the camera looks up her skirt from behind as she wavers on her feet before falling. Although it's unknown how the battle played out before Risako pulled out her gun, it's very likely that Misumi was winning the fight seeing that Risako had never previously used firearms in her battles and was seen on the ground sighing in relief that Misumi was defeated.
Risako then carries Misumi and walks with Karen to the basement entrance, where they throw Misumi's body onto the floor tile covering the passageway. Her body lands with her arms splayed beside her head and her legs spread, her skirt flipped up over her hips and exposing her panties, where the tiny yellow ribbon can be seen. After several seconds, the biometric lock deactivates and the floor tile opens up to reveal a hidden staircase.
Misumi is then seen carried down into the basement by Risako in Episode 3. After Aika defeats Kana and Rin, Risako and Karen meet up with her, with Risako still carrying the unconscious Misumi. Assuming the same biometric lock as the basement entrance, Risako attempts to use Misumi to open the door to the place where the captive girls are kept by spreading Misumi's legs and thighs and pressing her crotch and buttocks against the door. However, Misumi is unable to unlock the room, suggesting that she is of insufficient rank amongst the White Knights. She is then placed on the ground by Risako.
She was later used as a key to open the door to the main room.
Misumi's body is finally seen at the end of the episode, draped over a metal slab.