Police have charged six young men over a protest at Hawke's Bay Regional Prison's youth unit two months ago.
Six prisoners made their way on top of the roof of the unit at the prison near Hastings at the start of August.
They were there for about 24 hours - yelling, playing loud music and refusing to come down.
They were charged for rioting, intentional damage and assault.
Police said an 18-year-old man had pleaded guilty.
He will be sentenced in Hamilton District Court in November.
Five others are set to reappear in Hastings Youth Court in November as well.
The youth unit was closed after the protest due to significant damage.
The Department of Corrections earlier said it was reviewing the incident but that it would take some months.
RNZ has asked the Department of Corrections for an update on the unit and whether it is operating again.