Following a heated online debate on ways to combat groping and similar behaviors on trains, a name stamp-maker on Tuesday released a new product that can be applied to the offender’s hand — leaving the seal mark of an open palm to identify an assailant.

Developer Shachihata Inc., which makes easy-to-use pre-inked seals, hopes the product, priced at ¥2,500 before tax, will help deter the common problem on Japan’s crowded trains.

A limited trial run of 500 sets sold out in less than an hour after sales began at 1 p.m. Tuesday, company spokesman Hirofumi Mukai said.

The anti-groping stamp uses a special ink that only becomes visible under ultraviolet light, but not under sunlight or artificial light, according to the company. The black light that comes with the stamp can be used to illuminate the 9-millimeter stamped mark. The ink can be washed off.

Mukai said the product is designed primarily as a deterrent, to discourage anyone from groping. An accompanying strap can be attached to a bag to show those nearby that a person is carrying the stamp.

In May, a viral tweet about a school doctor who recommended pricking gropers using a safety pin generated mixed responses. Some said that would work as a deterrent, but others stated that the measure could be considered a crime. Shachihata then received a tweet suggesting the development of an anti-groping stamp. It was those discussions that propelled the company into action.

A tweet posted by the company on Tuesday said the launch of the product was “a small step” toward achieving a society where there are no sex crimes, including groping, and acts of violence.

“We will continue to consider ways for us to contribute to society,” the tweet said.

Yayoi Matsunaga, head of the Osaka-based organization Chikan Yokushi Katsudo Center (Groping Prevention Activities Center), said the same day that it was too early to judge whether or not the product can prevent groping but hailed Shachihata’s move as “very meaningful.”

The fact that a company released an anti-groping product “should have a big impact on society, which could lead to deterrence,” she added.

Following the trial sale, the company plans to revamp the product based on user feedback.