A Japanese court sentenced a former teacher to two years in prison for illegally taking and distributing indecent photos of students on social media. This action makes him the first member of the alleged ring to face a prison sentence in the high-profile case.

A Japanese court on Tuesday sentenced a former teacher to two years in prison for taking indecent images of pupils and sharing them on social media, making him the first among members of an alleged teachers’ voyeurism ring to receive a prison sentence in a high-profile case that came to light last year. The Nagoya District Court handed down the sentence to Katsuya Ishikawa, 28, who was a teacher at a junior high school in Hayama, Kanagawa Prefecture, at the time of his arrest in September. Judge...