Of persons sentenced to imprisonment with or without labor, those under 20 years of age at the time of sentence in the first instance are referred to as juvenile prisoners. Sentences for juvenile prisoners are executed in juvenile prisons or specifically designated sections in prisons in order to prevent adverse influences from adult prisoners and ensure sufficient education and training. Execution of sentences can be continued in the same prison until juveniles reach the age of 26 even after they reach 20. Juvenile prisoners who are under 16 years of age have become able to be treated at juvenile training schools until they reach 16 due to a partial amendment to the Juvenile Law, enforced on April 1, 2001. All juvenile prisoners whose sentences were finalized in 2002 were 16 years old or over.
  As of April 1, 2003, juvenile prisons have been established in 8 locations-Hakodate, Morioka, Mito, Kawagoe, Matsumoto, Himeji, Nara, and Saga.