The suicide of a 13-year-old boy in southern Japan after classmates systematically bullied him - even making him "practice" suicide - while teachers ignored the abuse or laughed has prompted soul-searching among educators across the country.

One of the boy's last acts was to text his tormentors and leave voice mails for them to say, "I'm going to die." They texted him back to say, "You should die."

The middle school student, whose name has not been released, jumped from his 14 th floor apartment in the city of Otsu last October after enduring heartrending tales of abuse at the hands of his classmates.

His father filed several reports with the police, but officers never accepted them, saying that they could not prove that bullying led to his suicide, according to Japanese media reports.

Details of the harassment are coming to light eight months later, following a student survey conducted by the city's board of education. In that anonymous survey, students write the bullying escalated to "punching and kicking" in September last year, about a month before the teen jumped to his death. The victim was pressured into shoplifting, had his legs and arms tied while bullies duck-taped his mouth. Students watched as their peers pressured the teen into eating dead bees, "pantsed" him, and made him "practice" committing suicide.

In the survey, some classmates report alerting teachers to those "practices," but say nothing was done.

Instead, teachers reportedly laughed as bullies tried to choke the victim.

"He was forced to eat paper, students choked him. Teachers only gave a verbal warning, but then joined in on the bullying by laughing," comments in the survey read.

Today, the tearful mayor of Otsu, said that she would launch a new investigation into the teen's suicide to "seek the truth," calling the board's survey "inadequate."

"I feel awful I have to put students through this again," Naomi Koshi said. "I cannot apologize to the students enough."

Local media report Otsu has been bombarded with hundreds of calls and emails from angry parents since the bullying came to light on July 4. A bomb threat was called into the board Thursday, forcing students to go home early.

The teen's family has not commented publicly on the case since the new details surfaced, but in a letter sent to Koshi, the boy's father called on the mayor to "seek the truth" and come up with a new anti-bullying policy.

"I want bullying to disappear from every school in Japan," he wrote. "I want schools to become a safe place again."