A 39-year-old public school teacher in Tokyo has been arrested for taking a video of the underwear of a third-grader in a classroom.

Koji Wakamatsu reportedly used a smartphone to film a girl’s undies while she was cleaning the classroom in June, Japan Today reports.

The offense was only recently revealed by an anonymous whistleblower who tipped the school off. School officials then called the police on 16 April.

Wakamatsu admitted to the voyeurism, telling police he had been secretly filming girls’ underwear since becoming a teacher 17 years ago. He said he had accumulated approximately 5,000 videos and images on his smartphone but deleted them, Japan Today quoted NTV as reporting.

Meanwhile, a medical underwear has been developed by microbiologists at the University of Maryland in College Park, USA, Science News (SN) reports.

The medical wearable collects data on how specific foods are fermented by gut bacteria and uses this information to help manage symptoms of gastrointestinal disorders such as irritable bowel syndrome and Crohn’s disease.

The “Fitbit for farts” (FFF) works by using chemical sensors to detect the frequency, duration, and gas concentration of flatulence events —around the clock, SN reports.

The FFF is seen as more reliable than previous methods of measuring flatulence, namely, invasive medical procedures or self-reporting, which could not account for gaseous emissions while the sufferers were asleep, according to SN.