A man who was driven by jealousy to repeatedly threaten the author of a popular teen manga series was sentenced to 4½ years in prison by the Tokyo District Court on Thursday.

Hirofumi Watanabe intended to severely disrupt the business of Tadatoshi Fujimaki, the author of "Kuroko no Basuke" ("Kuroko's Basketball"), with the threats, which lasted over a year beginning in October 2012, the ruling said.

Watanabe, a 36-year-old temp worker, sent death threats to organizers of several manga festivals in late 2012, demanding they cancel stage shows featuring Fujimaki's work and remove related merchandise.