Hana Midorikawa (緑川 花みどりかわ はな Midorikawa Hana⃝ℹ) is a supporting character of Prison School. She is a third-year student in attendance at Hachimitsu Academy[1] and the secretary of the Underground Student Council, a vigilante school organization.[2]
Hana is the fourth-best karate champion in the inter-high school championships.[3] She is a subordinate and loyal friend of Mari Kurihara, the president of the USC and she had an unrequited love interest in Kiyoshi Fujino. Hana debuted as a secondary antagonist, before she was imprisoned and subsequently allied with the boys against the Official Student Council. She became the main antagonist in the final story arc.

Personality
The first impression of Hana by the boys was that of a kind and cheerful individual. She enjoys brewing and drinking dandelion tea, and also has a love for four-leaf clovers. However, it was quickly shown that she can get very violent when angry, and expresses her anger with proficient karate attacks. Just like her peers, Hana displays a lot of hostility towards boys.
She is somewhat reserved in comparison to Meiko Shiraki (the Underground Student Council's Vice-President), wearing underlayers when on guard duty. She is actually very shy and impressionable, as shown when she is caught in compromising conditions by Kiyoshi Fujino a number of times. Hana is shown to be quite innocent in contrast to her more tough exterior persona, as she faints or becomes mortified when she finds herself in compromising or sexual situations.
Hana has a fear of mushrooms as a result of remembering the hospital visit. She has a mild obsession with Kiyoshi, which later develops into a crush after they kiss. Plot
After the boys intrude into the female bathing area of a swimming pool during the peeping incident, Meiko Shiraki (the USC Vice-President) and Hana capture four of the boys with Kiyoshi Fujino missing. The Underground Student Council President Mari Kurihara captures Kiyoshi & all of them face exclusion for the peeping incident, but are incarcerated in the Prison Block for one month instead. When the five first-year boys are detained, Mari assigns Hana to the boys instead of Meiko, as she is deemed incapable of disciplining the boys correctly due to their overarching lust sexualizing her attempts to beat them into submission. Hana puts her karate skills to use, with her powerful melee attacks to silence the students brutally.
During Kiyoshi's internal imprisonment, Hana had many awkward or embarrassing incidents with him, due to her initial encounter where Kiyoshi accidentally saw her urinating in the forest after she drunk too much tea
In their second encounter, she punished the boys and noticed Kiyoshi look at her and only glared at him. When he was alone, she confronted him about the incident and accuses him of telling his friends but learns he didn't tell anyone though she doesn't believe it as he again professes his innocence. Somewhat considering this, she tries to get her revenge on Kiyoshi by forcing him to pee in front of her, telling him if he did so then she'll believe him. and ended up getting urinated on, upon which she took a break from guard duty for a time. This leads to multiple times where she tries getting revenge only to fail each time, with each revenge attempt being caused by the previous encounter and her obsession with Kiyoshi only continuing to grow.
Upon her return, she participated in Mari's DTO, a conspiracy to force the expulsion of the boys from the school. After Jouji stabbed Kiyoshi by accident, Hana found another opportunity to harass Kiyoshi by bringing him to the school infirmary alone. Circumstances ended up that Kiyoshi and Hana ended up bottom naked and hiding together. Kiyoshi had an involuntary erection which was implied to have touched Hana's crotch and causing her to faint, with that traumatic memory temporarily blocked out. During the last day before the boys' impending expulsion, Hana's memory of the infirmary visit resurfaced and she attempted to kill Kiyoshi for that irreversible act before Meiko stopped her. As a last resort, Kiyoshi risked his life by using Hana's grudge on him as part of his plans to expose the USC's conspiracy. Hana took the bait and brought him alone to the guardroom, where she tearfully heaped physical abuse on him before forcefully kissing him, claiming by taking away his first kiss its revenge for the many slights he accidentally caused her. Kiyoshi then proceeded to incapacitate Hana by making out with her, allowing him to unlock the guardroom door without Hana's awareness. This gave the boys an opportunity to get evidence of DTO and expose the conspiracy to the Chairman.
During the confrontation in the Chairman's office, it was implied that Hana had fallen for Kiyoshi during the make-out incident. Upon realizing that Kiyoshi kissed her only for the sake of overturning the boys' expulsion, she attacked and injured Kiyoshi in a fit of rage. The Chairman proceeded to free the boys from imprisonment and overturn their expulsion. Hana and the two other members of the USC are placed in dorm arrest and subsequently forced by the official Aboveground Student Council to undergo incarceration in the Prison Block, due to their abuse and mistreatment of the prisoners and attempts to frame them violating the School Code. It was revealed that the USC's sentence would have been worse if it had not been for Kiyoshi's decision to not pursue the assault incident by Hana in the Chairman's office.
During the USC's imprisonment, Hana whines at her predicament and the Student Council attempts to alienate Hana from the other two USC members