Aoki Aka (赤 青黄, Aka Aoki) is a junior of Class 11 and the chairwoman of the Health Preservation Committee.
Aoki wears a serious expression most of the time and keeps a very emotionless face while speaking. She appears to hate Misogi Kumagawa, most likely because he sealed Najimi Ajimu in the past. Despite her calm demeanor, Aka quickly loses her temper when confronted by Ima Takarabe's stubborn refusal to be intimidated by her. She also quickly lost her composure and descended into panic upon realizing she could potentially lose her bet with Kumagawa (and be forced to wear nothing but an apron to school the next day).
Aka wears a burnt red nurse uniform along with matching gloves and light yellow stockings held up by suspenders. She has purple eyes, dark red hair and very long painted nails on her right hand. When dressed casually, Aka keeps her nurse's hat, but wears a white shirt with hearts on it, as well as dark colored gloves. She also wears a light colored belt with dark colored pants. Ten years later, Aka wears a lab coat over a turtleneck and skirt. She still wears stockings held up by suspenders.
Student Council Executive Arc
Kurokami Medaka's Successor Arc
After Kumagawa and Takarabe split up from Kouki Akune and Shori Wanizuka, they end up at the room where Aoki lays in wait. Already having administered her "punishment" to Kiki Kikitsu and Tsugiha Yojirou, she introduces herself and states the name of the challenge; "Palace of Pain: The Perfect Melancholy". The game involves matching cards. She spreads out 2 decks, including 2 jokers, over a table then explains the rules of the game. Takarabe, deciding to prove her worth, decides to try her hand at it. After her defeat Kumagawa steps in to take the punishment (a Summer fever). Kumagawa, now knowing the trick to the game, decides to step in. Aoki advises him against it, but he brushes her off. As soon as the games starts, Kumagawa summons his screws to keep all of the cards in place, stating that she's been switching cards to fool her opponents. As the game goes on, Kumagawa begins to take the upper-hand, and Aoki figures out that each screw is marked to identify same-set playing cards. She requests that he changes it back and the game resumes.
Near the end, it becomes apparent that Aoki will win and she requests that Kumagawa gives up. Kumagawa smiles, stating that the jokers haven't been drawn yet (drawing the jokers automatically switches the points of you and your opponent). Aoki, startled by this, starts to focus on locating the jokers. However by the time only 8 cards remained on the table, she has not found any. Aoki froze in fear as she saw that she has a 1/3 chance of going in nothing but an apron. She tries to appease him by offer to heal the ailments and even beg forgiveness. However Kumagawa refuses all her attempts and graciously allows her to wear her nurse cap with her naked apron tomorrow. Before Aoki made her move, Takarabe saves her by begging Kumagawa to stop. After the trial, Aoki warns the young girls to not get close to the Student Council as she cannot heal wounds in the heart. Afterwards, Kumagawa gave back the two Jokers he stole when Aoki attacked his arm. As the group leaves, she is bothered by how everything fell into Kumagawa's "calculations".
Unknown Shiranui Arc
Aka is approached by Medaka Kurokami asking about Hansode Shiranui; she assumes Medaka means Hanten Shiranui. When Aka tries to treat Zenkichi Hitoyoshi and Kumagawa, she is able to stop their hemorrhaging, but cannot close their wounds or restore them to consciousness. She asks Oudo Miyakonojou why neither Medaka nor Ajimu can treat the boys. Aka explains Zenkichi's and Kumagawa's conditions to Hitomi Hitoyoshi, who responds that this a job for a psychosomatic surgeon. After both boys are restored to consciousness, Kumagawa thanks Aka for looking after them, causing her to blush and look away, telling him there is no need to thank her. At the end of the academic year, Aka is among the students present at the Hakoniwa Academy graduation ceremony.
Bouquet Toss To The Future Arc
Five Focus (五本の病爪, Faibu Fōkasu): Aka has the ability to inflict diseases onto anyone that is scratched by her claws; Five Focus is a skill that manipulates aliments. The severity of the sickness can range from a slight fever to cancer. Aka can also remove ailments as well. Aka received this skill from Ajimu, along with the mission to prevent anyone at Hakoniwa Academy from dying. Takarabe labels Five Focus as a rare form of attack that makes Aka an area of effect skill holder. Takarabe believes this skill is very close to a Minus ability, and it is later confirmed as such by Maguro Kurokami.
- Her epithet, Red Angel, in Japanese is レッド エンゼル (Reddo Enzeru).
- When translated from kanji, Five Focus means Five Fingers' Diseased Nails.
- Aka was voted the seventeenth most popular character in the series in the third popularity poll with 128 votes.