Photo/Illutration Writing in a post on an online message board is identical to threats sent by fax to schools. (Tatsuya Sudo)

Threats of mass murder and bombings continued to be faxed to schools around Japan for at least three days, and one person may be responsible for most of them, The Asahi Shimbun has learned.

A post on a message board apparently by the threat-maker indicated that the perpetrator used a fee-based online fax service to send the threats.

Another post on the message board showed the names of schools that received the faxes.

Based on these posts, 15,178 threatening faxes were sent to 572 universities, 4,905 senior high schools and 9,701 junior high schools.

The writing in the message board posts was identical to some of the threats sent by fax, The Asahi Shimbun found.

The threats apparently started on the morning of Jan. 23, when universities received the menacing faxes.

“I’ve planted 334 bombs at your university,” the threat said.

“If you don’t want to die, put money into my bank account. You can do that, can’t you?” it continued.

The following morning, threats were sent to senior high schools.

“I will go on a killing spree with a homemade gun and firebombs,” it said.

In the predawn hours of Jan. 25, a note was faxed to junior high schools.

“I’ll kill you all with a survival knife,” it said.

The faxes all carried the name of an actual person, a lawyer in Tokyo.

Some schools closed early or shut down because of the threats.

In Saitama Prefecture, 136 prefectural high schools and 35 private schools received death threats via fax.

According to the prefectural board of education and other sources, more than 140 schools closed temporarily because of the threats.

A staff member at Nara Prefectural University in Nara, where 613 students attend, found two identical faxes were received around 8:30 a.m. on Jan. 23.

University staff and police officers patrolled the campus after those threats.

The university president and others discussed the matter and then decided to suspend classes from the afternoon.

“We have to take steps unless we can state with certainty that everything is 100-percent all right,” a staff member said.

The operator of the online fax service, a company based in Tokyo’s Chuo Ward, told The Asahi Shimbun in an email, “We have provided information to the Metropolitan Police Department and each prefectural police department.”