In Japan, a new mobile app is becoming all the rage among women. The app is designed to frighten away potential sexual harassers. Mayu Yoshida has more on why it's turned into such a success.

Every morning, millions of Tokyo residents brace for the notorious rush hour commute. Passengers can barely move at all and this is where women can become easy targets for molesters.

To scare them off, women in Japan are turning to a new app called Digi Police. The Tokyo Metropolitan Police released this app in 2016 with an anti-groping function. But when they revamped the app this year, officials say it really took off. Since then, it's been downloaded more than 270,000 times.

"When people freeze and become speechless after they encounter molesters, they can easily turn this app on."

"I'm not sure if I will be able to swiftly turn this app on but I saw this app on the news."

MAYU YOSHIDA TOKYO "This is how the app works. If someone encounters a groper, they can activate the app and show this screen to other passengers. This reads 'There's a groper here. Please help.' With another press, the message turns red and blasts a loud voice saying ('Yamete kudasai! Yametekudasai'), meaning 'Stop it.' It's supposed to help women feel safe on public transportation because according to recent data, 70% of women living in and around Tokyo have experienced sexual harassment on public transportation and roads."

Groping is a perennial problem in Japan and according to the National Police Agency, there are roughly 3,000 cases reported every year.

Some experts say the actual number could be 10 times higher because many groping victims choose not to go to the police.

SAKURA KAMITANI SEXUAL HARASSMENT LAWYER  "Most molesting cases occur inside crowded trains during commuting hours, so many women hesitate to come forward because they don't want to be late to school or work. It's also difficult to identify the culprit with five, six people squished around inside packed trains. Gropers also target younger women, such as students in uniforms, who look rather quiet. Also, the Japanese society's tolerance to groping incidents is making women not to make a big deal out of it."

To protect women, railways have installed women-only cars and more cameras to catch predators. But they still haven't disappeared. That's why female commuters are turning to technology because one push of this app could help them speak out. MAYU YOSHIDA, CGTN, TOKYO.