While changing attitudes to ensure it doesn’t happen in the first place, Japan is taking yet more measures to tackle a serious problem

Groping on public transport is a problem the world over, but the scale of it in Japan, where it is known as “chikan”, is infamous. According to Tokyo’s metropolitan police department, 1,750 cases of groping or molestation were reported in 2017, with more than 50% of sexual harassment cases occurring on trains, and a further 20% in train stations. Some reports suggest that more than 75% of all Japanese women have been groped.

No wonder women there are looking for a deterrent. Introducing the latest gadget: a stamp that brands gropers with invisible ink, which police can then reveal with UV light. It is the latest measure to try to fix the problem. Others have included women-only train carriages – which are still occupied by groups of men in protest, despite having been introduced over two decades ago – and an app that enables victims to play a voice shouting “Stop it!” at ear-piercing volume or bring up a full-screen message reading: “There is a molester. Please help,” to other passengers.

That app, which as of earlier this year had been downloaded 237,000 times, I imagine to be basically the digital equivalent of my friend announcing loudly on the bus: “Could you please remove your hand from my arse?” Public embarrassment provoked by some choice, assertive words can prove effective – yet not every woman feels comfortable taking that route.

The invisible ink, however, seems like a true case of parking the ambulance at the bottom of the cliff. While any measure that increases women’s sense of safety and the likelihood of conviction is to be welcomed, it does not solve the underlying problem of men failing to accept women’s bodily autonomy. That requires widespread structural change (and perhaps, you know, the overthrowing of the patriarchy).

In the meantime, some measures have been shown to be effective. Transport for London’s Project Guardian initiative in 2013 aimed to increase the number of women reporting sexual assault on public transport, and recorded some success through a combination of better reporting resources (you could do so via text message), more plain-clothed officers, and an awareness campaign.

It may be less exciting than invisible ink, but it might work.