en PortalulTauTV. "A School Behind Bars" centers around Asahi Junior High School, which is located within Nagano Matsumoto Boy's prison in Matsumoto City, Nagano Prefecture - the only public school in Japan that is located inside a prison. The school's students are all prisoners ranging in age from 20-70. The students are carefully selected after taking an entrance exam and being selected by the school's admission board.