The story follows a young boy who enrolled in the former all-girls school, Hachimitsu Academy.With over 1,000 female students and only 5 males, initially the school looks to be a paradise.
But darker forces, unhappy with the admission of boys into what was once a safe haven for girls, are afoot, waiting for a chance to drive the boys out and restore the school to its former glory.
Above Ground Student Council
The Above Ground Student Council is introduced by Anzu to the boys as an official organisation that fulfils the normal function of a Student Council but does not enjoy the popularity of the Underground Student Council.
The Above Student Council makes their appearance when they incarcerate the active senior members of the USC in the school's Prison Block for violating the school rules and abusing the boys.
Underground Student Council
The Underground Student Council is a fictional organization in Prison School that enforces the traditional rules of the school code of the Academy.
Controlled by the President (& crow-user) Mari Kurihara, they enjoy a historically elevated status in the school, with their own designated school office and faculty influence.
Though a vigilante organisation, they enjoy more student popularity than the Above Ground Student Council.
The private all-girls school Hachimitsu Academy stands on the outskirts , a strict boarding school for sporting elite young women that upholds traditional rules on its campus.
However, the new academic year sees the reform of one tradition: the admittance of male students.
Though the few accepted boys including Kiyoshi Fujino are thrilled by this discovery, only five boys enter the cohort with a 1:200 boy-to-girl ratio on the first day of school.
To their dismay, their adolescent dreams are crushed when they are unable to interact with the schoolgirls due to the written threats of the misandric Underground Student Council. The infiltration of the girls' bathing area by the five boys results in their internal imprisonment in the school's Prison Block, where they receive an ultimatum from the USC to stay a month in the prison or be expelled.
Chiyo has a kind personality, and is notably one of the only female students not opposed to the admission of boys in the Academy.
Her commitment to sumo wrestling is what inadvertently results in meeting Kiyoshi Fujino & befriending him.
Chiyo's love of the sport is strong enough that that she believes that any fan of sumo wrestling cannot be evil.
Unless you can get past the initial outlandishness of the series, you probably won’t enjoy what the series has to offer down the line.
But once you get hooked, there is no turning back.