The Tokyo metropolitan board of education has reprimanded 57 teachers, assistant principals and principals at eight high schools for failing to inform pupils properly that they must stand and sing "Kimigayo" at enrollment and graduation ceremonies.

Tuesday's punishment of 43 teachers and 14 assistant principals and principals is unusual in that it is the first time teachers have been punished for the behavior of students who refused to stand during the anthem.

Previously, teachers had only been punished if they themselves disobeyed the school board rule to stand and sing the anthem.