A viral stunt inside a Japanese zoo has triggered legal action and a swift crackdown on visitor behaviour after two American tourists allegedly trespassed into a monkey enclosure housing nearly 60 animals.

The incident, which happened on 17 May, has stirred up new worries about what social media-driven antics can do in sensitive wildlife spots.

Investigators say Reid Jahnai Dayson, 24, and Neal Jabahri Duan, 27, supposedly conspired to film some kind of stunt inside the monkey enclosure at Ichikawa City Zoo in Chiba prefecture.

Reportedly, one of the men climbed over a barrier while wearing a character style costume, while the other hung around on the far side of the fence, filming the moment, before later posting the clip online.

Zoo staff stepped in before either person could get near the animals. Authorities say they have since referred both men to prosecutors, on suspicion of forcibly obstructing business operations, which is a bit of a mouthful, really.

The enclosure is where Punch lives, a young macaque that went viral earlier this year after a video showed it clinging to an orangutan plushie. That clip pulled in huge crowds to the zoo. Because of that, officials introduced tighter viewing limits to curb stress on the animals.

When the incident happened, Punch and dozens of other monkeys were there too, so the risk of disruption or even harm felt higher than usual.

Because of all this, the zoo has widened the buffer zone around the enclosure, put in anti-intrusion netting and started constant patrols. Officials are also weighing a full prohibition on photography and filming near the monkey habitat, just to be safe.

Zoo authorities say the intrusion put both staff and animals at risk. Local officials have emphasised the need for stronger safeguards to prevent similar incidents, especially as viral trends increasingly intersect with public spaces.

For visitors hoping to catch sight of Punch, the experience is now more controlled, and it reflects a wider shift towards prioritising animal well-being over unrestricted access.