A TV Asahi drama producer's 2015 death due to heart failure was determined by labor authorities later that year to be caused by overwork, sources close to the matter revealed Wednesday.

A local labor standards office found the producer, who was in his 50s, had worked up to 130 hours of overtime per month, leading to his death in February 2015. He was in a managerial and supervisory position and thus his working hours were not restricted under the law.

The revelation follows the April 21 death of a 49-year-old male editor who was loaned out to TV Asahi from its subsidiary, and the 2013 death from overwork of a 31-year-old female reporter at the Japan Broadcasting Corp. (NHK), highlighting the grim working environment of the Japanese media industry.