Warning label for other passengers seems to have been secretly slapped on.

Chikan, or train gropers, take advantage of the environmental conditions on Japan’s urban rail lines, copping a feel on targets when they’re distracted from being in a hurry and/or already being in such close proximity to so many other people. But one accused chikan in the Tokyo area looks to have let his own guard down.

On Wednesday morning, Japanese Twitter user @Yammer_1 was on the Musashino Line, which serves the suburbs of Chiba Prefecture that lie east of downtown Tokyo. After getting on the 10:22 train from Nishi Funabashi Station, but before arriving at her destination, Maihama Station (the closest stop to Tokyo Disneyland), @Yammer_1 snapped the following pictures.

https://twitter.com/Yammer_1/status/978808848570970112

Stuck to the back of the man’s sweater is a sticker that reads “Kono hito mainichi chikan shiteimasu,” or “This person is groping people on the train every day.” Sure enough, in the first of the three photos, he can be seen extending his right hand, concealed by the jacket draped over it, towards the posterior of the woman standing next to him.

Some Twitter users speculated this might be a staged attempt at humor, or that maybe the man himself was the victim of a prank. It does seem kind of odd that someone would bother putting a sticker on the back of someone who’s holding a jacket, which he’ll eventually put on and cover up the warning/accusation. However, @Yammer_1 says the man indeed start touching the woman with his hidden hand, and kept it up for an extended period of time. Though @Yammer_1 initially thought the two might be acquaintances, the man and woman exchanged no words that indicated any sort of existing relationship in the 12 minutes @Yammer_1 spent on the train before getting off at Maihama, at which point the man in the photo and the woman next to him remained on the train which continued on towards Tokyo.

Twitter commenters have been nearly unanimous in their denouncement of the man’s actions, but some have also expressed disappointment that whoever wrote the sticker apparently had the courage to stick it on the man’s back, but not to contact the authorities after ostensibly witnessing him repeatedly grope women on the train. Similarly, more than one commenter encouraged @Yammer_1 to submit her photos to the police, since if the man is traveling on the same line frequently enough to have the sticker’s author recognize him, it stands to reason that investigators should be able to track him down. One commenter even suggested that had @Yammer_1 recorded video instead of taking still shots, an even stronger case could be built against the man, like what happened when a man in Tokyo was arrested after being filmed taking illicit upskirt videos.

Meanwhile, this is a good time to remember that unfortunately not all chikan come with visible warning labels, so it’s always a smart idea to stay aware of your surroundings when riding the rails.

Source: Twitter/@Yammer_1 via Hachima Kiko