Japan's education ministry has published a letter purportedly from a school pupil threatening suicide on Saturday if he continues to be bullied.
Education Minister Bunmei Ibuki made a personal plea to the child
The Japanese education minister received a package of letters from the child anonymously on Monday.
The ministry has asked education boards across the country to check whether any pupils in their district have problems similar to those described.
The contents of the letter have been published in Japanese newspapers.
It is hard to tell whether this is a genuine cry for help or not but the ministry is taking no chances, says the BBC's Chris Hogg in Tokyo.
At a news conference on Tuesday, chief cabinet secretary Yasuhisa Shiozaki stressed how seriously the threat was being taken.
'Living is painful'
"This is a matter of life and death," he told Reuters news agency.
"We want him (the pupil) to treat as precious the life received from his parents and ancestors."
The package sent to the ministry included letters intended for the education minister, the child's bullies and his parents.
In the letter addressed to Japan's Education Minister Bunmei Ibuki, the pupil - who is believed to be a boy - complains that he is being bullied and those responsible have not been punished.
"I am writing this letter because living is painful," the letter said.
"If nothing has changed by Wednesday, 8 November, I will commit suicide."
You have only one life and that life is not yours alone.
Japanese Education Minister
In a note to the bullies the boy asks why they are picking on him. Another note addressed to a teacher asks why they will not help him.
Also in the package were other notes to officials, a school principal, and to the boy's own parents. To them he says simply: "I am sorry."
None of these letters gives enough information to identify the pupil.
All the authorities have to go on is one character on the postmark, which could help to narrow down the search for him.
Education boards have been put on alert across the country in the hope they can prevent him carrying out his threat.
At Tuesday's press conference, Mr Ibuki made a personal plea to the child, saying the child's life was not his alone to take.
"Your mother and father brought you into this world, holding you in their arms," he said.
"I want you to understand that you are not being left alone."
Bullying is a real problem in Japan. Three bullied teenagers have taken their own lives in Japan since August.
The authorities have been trying to come up with ways to tackle the problem, but they are not finding it easy.