A slice of Tokyo's trade-fair world took a crime-drama turn this summer. Police arrested a 55-year-old Colombian man on suspicion of swiping jewellery and gemstones worth around ¥39 million from a booth at Tokyo Big Sight, the cavernous exhibition centre in the Ariake district on Tokyo Bay.

The theft happened on July 5, at about 5:05 p.m., right as a jewellery exhibition was wrapping up its final day. According to NHK, investigators believe the man slipped into the venue as if he were an ordinary visitor, then took a carry case from the booth of a Kobe-based jewellery store while staff were packing up. The haul: 137 items, including diamonds, rubies and rings.

The suspect, identified as Ernesto Gutierrez Torres — listed by police as having no fixed address or occupation — has denied the allegations, telling officers he took nothing and knew nothing about it. What makes the case notable for travellers is the cross-border element: he left Japan on July 12, but was taken into custody on Monday when he flew back into Narita Airport from Colombia. Japanese police were clearly waiting for him.

Tokyo Big Sight (officially Tokyo International Exhibition Center) is one of Asia's busiest convention venues, hosting everything from anime fan events and food expos to trade shows like this jewellery fair. Incidents like this are rare — it's a heavily staffed, camera-covered environment — but the story is a useful reminder for anyone exhibiting or shopping at fairs: the busiest risk window is often teardown time on the last day, when attention shifts to packing and security thins out.

For travellers, this isn't a safety alarm so much as a window into a side of Tokyo most visitors never see. Ariake itself is worth a look if you're in the Odaiba area — it's near thePalette Town zone, the Giant Sky wheel views of the bay, and the ryotsu-mon arches of the venue that anime fans will recognise from countless conventions. If you're attending a public trade event or exhibition during a Japan trip, keep valuables close and be aware at start-up and close-down times, just as you would at any crowded event anywhere.

Who's this story for? Mostly the curious: travellers who love a good true-crime footnote, plus anyone planning to exhibit or buy at a Japanese trade show. It's also a small nod to how efficiently Japanese police work international arrivals — even a flight back from South America didn't end the investigation.