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

Shinnosuke Komatsuda, who died Sunday, left a journal entry criticizing his school for its lack of response to his repeated pleas for help, the sources said Monday.

A third-party committee formed by the Kawaguchi Board of Education is looking into the alleged bullying and confirming details about the boy's death. Officials have not said which junior high school the boy had attended.