七囚人 seven_prisoners
The Seven Prisoners (七囚人, Seven Prisoners) are a group of problem students in Kivotos.

Seven Prisoners is an umbrella term used to refer to the seven students that broke out of the Correction Bureau after the General Student Council President's disappearance. Because only problem students are sent to the Correction Bureau, all seven students belonging to the Seven Prisoners are extremely dangerous, in one way or another.

https://bluearchive.fandom.com/wiki/Seven_Prisoners
seven prisoners (blue archive)