Misumi has spiky black hair and wears a pair of glasses. She is is noticeably smaller sized than the rest of the girls, Nanami being the closest to her in stature. She wears the white dress worn by all White Knights, along with distinctive 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. Here she has Nanami draped over her shoulder who was defeated by Aika.
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 violently. However, the White Knight manages to easily recover herself mid air and lands unharmed on a sofa, to which both Risako and Karen react with evident shock. Misumi then laughs diabolically and rises, before cracking her nuckles in an ominous manner and presumably attacking.
Unfortunately for her, Risako turns out to be armed and the White Knight does not get to show the full extent of her combat abilities before hastily being put down with a well aimed shot. Next thing we see when we get back to the fight, Misumi is struggling to barely stay standing and the camera indulges on looking up her skirt from behind as she wavers on her feet, before finally collapsing, presumably over the arm of a couch.
Although it's unknown how exactly the battle was playing out before Risako pulled out her gun, it's very likely that Misumi was winning, since Risako had never previously used firearms in her battles and she was also later seen on the ground sighing in relief that Misumi was down.
Risako then gets a hold of Misumi's unsconscious body and carries it on her shoulder to the place where Karen think she has discovered a hidden entrance. Here, Risako uncaringly throws Misumi's body directly over the floor tile covering the passageway, rather than delicately leaving it on the ground, maybe still annoyed over all the troubles the White Knight had put her trough. Her body lands with a hard thud, arms splayed beside her head and legs spread, the girl's short skirt flipped up over the hips, clearly 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 in a manner identical to a trap door, taking Misumi's body with it in the process. Given the position the White Knight was in prior to the opening, her body ends up lifted together with the acces tile, remaining over the open passageway, her legs hanging freely over the misterious opening, as if framing it.
Misumi is then seen in Episode 3 being carried further down into the basement by Risako, probably for her body to be used as a key if necessary. 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 in 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, this time much more gently than the last.
Misumi's body is finally seen for the last time at the end of the episode, draped over a metal slab tothether with the rest of the captured White Knights. Her body lies between Reiko and Manami, where her smaller size is evident but does not deter her ass from being one of the most remarkable of the bunch. Strangely enough, despite the whole ordeal, Misumi still has her glasses.
Misumi is the only White Knight who never openly faces Aika in combat, only battling against Karen and Risako and being defeated by them. She is also the only girl besides the main leaders (ETAI, Miyu, Kana and Rin) who does not get captured by the alien tendrils after her defeat, since Risako decides to carry her body around to use it as a key.
Aika R-16 Paralellism
Misumi continues the unnamed "comic" tradition established in Aika R-16 of having a great build-up for an enemy's fighting skills only for the girl in question to then be defeated in a fairly cheap and unexpected manner.
In Aika R-16 this happens with Karate Girl in Episode 2 who, after showing off her skills for several seconds, ends up being put down by a golf club thrown by Karen accidentally hitting her in the head. In a similar way, in Aika Zero, the whole Misumi incident shows her as a highly dangerous foe, who not only has great combat skills but also even feels confident enough to take the freedom to mess with her enemies, constantly laughing, grinning and displaying her talents without any need to hurry and finish them off, as if they were no real threat. This makes everyone think we are about to see a fairly interesting and difficult fight and yet, when we get back to Misumi, she's been put down off camera with a tranquilizer dart in the most anticlimatic way possible.
In what's probably a fundamental part to both girl's tragicomic defeat, Karen is always involved.