Hakama Shiranui (不知火 袴, Shiranui Hakama) was the chairman of Hakoniwa Academy and the coordinator of the Flask Plan. He is the grandfather of Hansode Shiranui. He is one of the central antagonists of the series, being responsible for much of the conflict Medaka Kurokami faces during her time as Student Council president.
Hakama is usually quite congenial, as he jokes around with Abnormals and always tries to keep a smile on his face. Behind the smile though, is a smart, ruthless mindset that has allowed Hakama to successfully run the Flask Plan for years. Even after being attacked by Misogi Kumagawa, Hakama remains focused on pursuing his own ends, and decides to let Kumagawa run wild to keep Medaka occupied. When he's near his granddaughter, he becomes more bonhomie and treats her like a child (despite her being a high school student), but he still recognizes her intelligence and listens to her advice.
Hakama is an typically elderly man with a wrinkled visage, white hair, beard, and blue eyes. Like other members of his family, his hair is styled with a large ahoge, similar to his granddaughter's. Hakama wears a purple hakama beneath a golden vest with two red stripes. He is almost always seen sitting, and very rarely stands. When his darker nature surfaces, Hakama's eyes are shown as black.
In order to act as an agent for Kajiki Kurokami, Hakama became the chairman of Hakoniwa Academy. He is thought to be more qualified than Kajiki himself. When he became the chairman, Hakama abolished the academy's mental training for being too dangerous. While searching for candidates for the Flask Plan, Hakama approached Shigusa Takachiho to personally invite him to the project.
Student Council Executive Arc
Thirteen Party Arc
Hakama meets with Medaka in his office, thanking her for getting Unzen under control, and after briefly discussing his granddaughter, he asks Medaka if she would be willing to take Unzen's place in the Flask Plan. Hakama goes on to identify Medaka as an Abnormal, and when she denies his assessment, he asks her to try an experiment with dice. When Medaka rolls eight dice at once, they form into a tower, a result that amazes Hakama. He then goes on to explain that the Flask Plan needs thirteen members, all of whom are chosen from Class 13, and while freshman are not usually allowed into the Flask Plan, Medaka's defeat of Unzen qualifies her to participate. Medaka turns him down however, and leaves. Hakama thinks to himself that Medaka is very strong, but that that also makes her weak points very easy to find. He then addresses the six members of the Thirteen Party concealed in his office, asking their thoughts. After hearing their assessment, Hakama thinks to himself how difficult they are to handle, but that at least these six bothered to answer his summons. He assures Itami Koga that he will convince Medaka to join the Flask Plan, but expresses his concern for her safety. Hakama details the history of the Flask Plan, culminating with his belief that the project has reached the final step with the present incarnation of the Thirteen Party.
As the Student Council invades the Flask Plan labs, Hakama watches their advance on a monitor. Hakama expresses his surprise at Medaka's companions: one Normal, Zenkichi Hitoyoshi, and two Specials, Kouki Akune and Mogana Kikaijima. He asks Shiranui if she is planning anything. After she denies it, Hakama notes how Oudo Miyakonojou's actions turned out to work in his favor, as he never expected Medaka to come so soon. Shiranui warns him not to ignore Akune and Kikaijima however, as one of Medaka's greatest assets is her authority over those around her. Hakama chuckles, remarking that it is rare for Shiranui to give him a warning. To himself, he decides that the most interesting member of the party is Zenkichi, whose birthday was somehow selected as a code for the Door of Rejection. After Medaka's fight with Takachiho ends, Hakama comments to Shiranui that all Abnormals want to have relationships, but their overwhelming abilities make this impossible. He remarks that as long as Medaka is in the complex, he will make use of her as a guinea pig. When Shiranui asks him who is on the next floor, he tells her that it is Kei Munakata, who isn't as strong as Takachiho, but is on the nation's most wanted list for mass murder. In his office, Hakama makes a phone call, requesting the file on Munakata be gotten rid off. He states that Munakata will stay on the right path, but expresses his annoyance that Munakata befriended Zenkichi, when Hakama wanted him to befriend Medaka. Hakama labels Zenkichi as a wolf in sheep's clothing; a Normal who could fight an Abnormal. He watches Shiranui leave without comment, then decides that if even Maguro Kurokami has shown up, that the Flask Plan is in need of adjustments.
Kumagawa Incident Arc
In his office, Hakama is surprised to hear Kumagawa's reason for transferring to Hakoniwa Academy. Hakama is put on guard by Kumagawa's attitude, but agrees to make him some tea. Preparing the drink, Hakama thinks to himself on all that has happened that day, and considers how to fall back on his Plan B for the Flask Plan. Observing Kumagawa, he decides that a Minus is really quite remarkable. After serving the tea, He asks Kumagawa what his plan is by transferring to Hakoniwa Academy; what more efficient way has he come up with to achieve a peaceful world. Hearing Kumagawa's plans to execute all of the elites, Hakama is horrified, and realizes that Kumagawa is more of a dangerous element than he realized. Hearing Kumagawa's reasons (or lack thereof), Hakama loses his patience, stating that Hakoniwa Academy is an educational institute. He is then attacked by Kumagawa, several screws imbedded in his body. Kumagawa then puts another screw through his head. Hakama is shocked to find himself suddenly unhurt however, his body and even his clothes fine. Hakama thinks to himself that he has seen over a thousand Abnormals pass through Class 13, but Kumagawa is different from anyone else; yet for that very reason, he just what is needed to create a minus perfect human. Hakama decides to let Kumagawa go about with his own devices; Hakama will test out his own theories in the meantime. As Kumagawa makes to leave, Hakama questions what Kumagawa intends to do about Medaka; Kumagawa replies that he will settle his score, but that he has no intention of fighting her. After Kumagawa has left, Shiranui enters Hakama's office, asking her grandfather to let her into Class -13. After the conclusion of the election battles, Hakama meets with Najimi Ajimu and Hanten Shiranui in his office. Hakama offers to transfer them into Class -13, an offer Ajimu turns down for both herself and Hanten.
Kurokami Medaka's Successor Arc
Jet Black Bride Arc
Hakama meets with Maguro and Kajiki Kurokami to discuss the second Jet Black Wedding Feast. Hakama wonders why Maguro has not interfered; who admits his father has ordered him not to. Hakama questions why Medaka loves Fukurou Tsurubami as a father, though Maguro tells him he is looking at the question from the wrong end. He then explains that Kajiki married all seven suitors when he came off age, a revelation that shocks Hakama. He listens quietly as Kajiki explains the Kurokami family's excessive love. Informed by Maguro that the Jet Black Wedding Feast has ended, Hakama remarks that it is a natural outcome for a member of Hakoniwa Academy.
Bouquet Toss To The Future Arc
When Medaka turns in her withdrawal notice, Hakama questions if she won't change her mind, but accepts her decision. Hakama awaits Medaka to challenge her as part of the 100 Flowers Run in his office, along with Kajiki, Nashi Kurokami, Hitomi Hitoyoshi, and the academy's teachers. He tells Medaka that, as adults, they do not need to rise to fight a child. His message to Medaka is that it was a good springtime of youth. Come April of the new school year, Hakama retires from his position as chairman, Medaka succeeding him.
- The members of the Shiranui family are named after articles of clothing. Hakama is a man's formal divided shirt.