A video of an argument between a pupil and a teacher at a Japanese high school that ends with the teacher punching the boy has gone viral, sparking a fierce debate over violence in schools and the pressure school staff are under.
The 74-second clip, apparently filmed by students who were watching the confrontation, initially shows the teacher talking with the 16-year-old boy in a hallway at Machida Sogo High School, in west Tokyo.
The boy had reportedly been reprimanded for wearing an earring, in contravention of the school's dress code. The teacher appears calm at the outset, while the boy yells at the teacher: "Use that tiny brain of yours. Think about it!"
He later adds: "Are you a damned idiot?"
The dispute, which took place on January 16, suddenly escalates when the teacher, who has not been named, takes a step forward and punches the boy. The pupil falls to the floor but the teacher grabs him by one arm and stands over him as a group of pupils spill out of a nearby classroom and attempt to intervene.
The pupil reportedly suffered bruising to his face and a cut to the inside of his mouth.
The school has issued an apology to the boy's parents and the teacher - who local media have reported has no previous record of resorting to violence against a student - issued a statement of apology.
"I lost my temper at the student's words and became violent," he said in the statement. "I regret my actions."
The boy's parents have made no comment on the incident.
The school is considering disciplinary measures against the teacher and is in discussions with the local education authority and the police over whether criminal charges should be filed.
Since the video clip went viral on social media, the discussion has become polarised, with many commentators insisting that a teacher is never right to hit a child - but there were plenty who seemed to side with the teacher.
"The teacher is flat out, 100 per cent wrong here," was one comment on the Japan Today website. "No matter what a student says, the teacher has no right to assault him. His job was to defuse the situation … he escalated it because he had no self control. He should be charged!"
Another asked, "Why didn't the teacher walk away? Why did the teacher escalate the problem by pushing the boy? Because the teacher himself was on a power trip. He was in effect bullying the boy into submission and proves it by assaulting him!"
Taking the other stance were comments saying that children needed to be more respectful towards their teachers. "Kids need to show more respect for their elders. Too many parents these days, both here and abroad, side with their kids too much in a situation like this," said one.
Support for the teacher seems to be widespread - a change.org petition set up demanding that he be fired had attracted only 39 signatures in four days as of Wednesday - although the National Teachers' Federation is choosing its words very carefully as the debate heats up.
"A teacher should never use violence against a student and we want all our members to be able to communicate with pupils, to be patient and to avoid any kind of violence," said Tamaki Terazawa, a spokeswoman for the federation, told the Post.
"But we recognise how hard that can be in certain situations, and this was one of those situations. It is clear from the video that the teacher did try to speak calmly with the boy, but his behaviour was very bad."
The union is calling for the education ministry and local education authorities to improve working conditions for teachers - who on average work 80 hours a week, the highest of any nation in the Organisation for Economic Co-operation and Development bloc - to help resolve classroom issues.
Makoto Watanabe, an associate professor of media and communications at Hokkaido Bunkyo University, said there had been a growing trend among male teenage students to cause problems in classrooms, often as they "show off" to their classmates.
"When I was a boy, our teachers would shout at us or give us a slap around the head, but pupils nowadays know that a teacher cannot touch them because of the ministry's rules," he said. "That means that they have become bolder and that whatever they do, a teacher should never react with violence.
"That is why so few teachers want to work in junior or senior high schools, particularly in areas that have a bad reputation. It seems to me that all the focus has been on the human rights of the students, but what about the human rights of the teachers?"
This article was first published on South China Morning Post.