KOFU -- A high school teacher angered over a student's hairstyle repeatedly slapped him and then shaved his hair off with other students, the Yamanashi Prefectural Board of Education has disclosed.

The Kofu Josai Yamanashi Prefectural High School teacher, who is in his 50s, became angry when the student came to school on Oct. 24 with the sides of his head shaved, according to the education board. The teacher, who served as deputy advisor of the school's sports club, called the student to him and slapped him in the face roughly 10 times before shaving off the rest of his hair.

The teacher, who had been coaching the student in after-school club activities, also forced three other third-year students from the club to participate in shaving off the student's hair, while the advisor to the club, also a teacher in his 50s, was at the scene and did not intervene. The three male students have joined in taking collective responsibility for the incident.

The principal of the school found out about the punishment the day it occurred from another teacher, and reported it to the board of education. The principal and the two teachers involved visited the homes of all four students involved to offer their apologies, the board of education said.