A 15-year-old boy who had previously complained about being bullied at school has died in an apparent suicide after falling from a building in Saitama Prefecture, investigative sources said Monday.

Shinnosuke Komatsuda, who died Sunday after falling from an apartment building in Kawaguchi, left a journal entry criticizing his school for its lack of response to his repeated pleas for help, the sources said.

A third-party committee formed by the Kawaguchi city board of education was looking into the alleged bullying at the unnamed public school and is confirming details on the boy's death.

"The board of education are huge liars. They protect the bullies and lie," he had written in a journal entry dated Sept 6, according to the sources. "Why does someone who is bullied like me have to suffer so much?"

The boy's mother, whose identity has not been publically released, was scathing about her son's treatment.

"My son was betrayed by the school, abandoned by the educational board and harmed by the perpetrators," Komatsuda's mother said after his death. "Please thoroughly investigate the cause, even if from now."

Komatsuda started at the junior high school in April 2016, according to the city's educational board. The bullying began around May when classmates and older students from his after-school soccer team started to insult and ignore him.

Komatsuda handed letters to his homeroom teacher several times pleading for help in September 2016, but the school's lack of response apparently led to his first suicide attempt, investigators said.

Source: ANNnewsCH