Chobatsu literally means "punishment", but the word commonly refers to a specific practice in Japan
This involves putting prisoners in isolation and forcing them to sit on a small plywood box with a 5-inch ledge in the rear that makes it painful to lean back.
During a period of chobatsu, everything is taken from the prisoner's cell and the windows are covered over. He is made to sit up straight on the box, knees together, elbows tucked in, hands flat on his thighs, feet on the floor, staring at the wall for 12 hours a day. An inmate can rise from the box for meals but must return to it immediately. He can take a shower after 10 days. The guards (who must be referred to as sensei) will shout if they see even one finger out of alignment.
This strict discipline and isolation are meant to elicit remorse and prompt prisoners to reflect and change their ways.
In fact, it is not at all unlike Zen Buddhist sesshin or Morita Psychotherapy.
Except that in those cases the discipline is freely chosen and is guided by a context of either deep training or a therapeutic commitment.
Former prisoners say chobatsu can be administered for just about any infraction, from opening their eyes to talking in the factory bathroom.