Invisible-ink stamps to identify gropers on public transit sell out in minutes

(CNN) – Japanese inventors have found a way to discourage rush-hour groping in crowded areas.

This stamp allows victims of harassment to mark their assailants with invisible ink.

The mark is in the shape of a hand and shows up under certain types of light.

The company says it developed the stamp after seeing discussions on social media.

Women in Japan have long looked for ways to stop sexual harassment on crowded trains and public transportation known as Chikan.

The company hopes the stamp will act as a deterrent to would-be attackers.

A test run of a stamp prototype sold out in less than 30 minutes online.