Visitor interest in Japan plunged in June, amid a prophecy in a manga that predicted a “disaster” would strike Japan in July 2025.

The prediction was in a 2021 reprint of a Japanese comic book, or manga, titled “Watashi ga Mita Mirai, Kanzenban” (which translates to “The Future That I Saw, Complete Edition”) by artist Ryo Tatsuki.

In the original printing of the book in 1999, the cover page referenced a “disaster in March 2011.”

In March 2011, Japan suffered its most powerful earthquake on record, the Great Tohoku Earthquake, which caused almost 20,000 deaths and the Fukushima Daiichi nuclear disaster.

The Amazon listing for the reprint stated that the author had “new prophetic dreams” including the “real disaster will come in July 2025,” according to a Google translation.

CN Yuen, managing director of Hong Kong-based travel agency WWPKG told CNBC that the rumor was widely circulated in Hong Kong, where it spread over mainstream media, TV networks and through YouTube influencers.

Visitors arrivals from Hong Kong plunged 33.4% year on year in June, following an earlier 11.2% drop in May, according to Japan’s National Tourism Organization.

Yuen said his agency has seen a 50% decrease in bookings and inquiries in April and May to Japan from last year.

Tourist arrivals from other Asian countries also experienced slower growth. Arrivals from South Korea rose just 3.8% in June compared with May’s 11.8%. Arrivals from Taiwan slowed significantly as well, from a 15.5% increase in May to 1.8% in June.

Overseas visitors to Japan grew 24%, on average, from January to May of this year, compared to 2024. But June arrivals only saw a 7.6% increase, according to Japan’s travel statistics.

WWPKG’s Yuen said he is used to travel downturns related to natural disasters, which usually end after the incident is over.

But “this time, it’s different, because nothing happened actually. It’s only a rumor, or prophecy,” he told CNBC. “This is the first time we’ve seen such an incident.”

Hong Kong and Japanese media reported earlier in July that Hong Kong airlines cut flights to some Japanese cities, including Nagoya.

A January report from Japan’s Asahi Shimbun, citing the country’s Headquarters for Earthquake Research Promotion, also warned that the likelihood of a megaquake in the next 30 years had risen to 80%—a development that, combined with the prediction, created a “perfect storm” to deter travelers, Yuen said.

However, Japan’s Meteorological Agency said: “It should be noted that the issuance of information indicating elevated potential for a Nankai Trough earthquake does not necessarily mean that one will actually strike.”

JNTO data showed that the share of Asian tourists fell year on year in June, but that of Western countries rose.

Experts CNBC spoke to gave various reasons, including cultural ones.

“Manga is not just entertainment; it is widely read across age groups and carries a bit of cultural authority in some Asian societies,” said Zimbayah Kamble, a senior lecturer for hospitality at James Cook University.

That, combined with memories of past disasters and the reality of Japan’s seismic vulnerability, mean that such warnings “resonate strongly” in the region, she said.

Kiattipoom Kiatkawsin, associate professor of hospitality and tourism management from the Singapore Institute of Management, said the rapid spread of the rumors through social media platforms and the collectivist nature of many Asian societies led to a social amplification of perceived risk.

“This means that even if some individuals have doubts, the collective response of their community or peers can significantly influence their decisions, leading to widespread behavioral changes, such as travel cancelations,” Kiatkawsin said.

“In this case, a fictional narrative amplified by social media could have created a compelling, if scientifically unfounded reason to defer travel,” he said.

But both experts also pointed to a more ordinary reason: the flexibility of short-haul travel.

Kiatkawsin said the costs of canceling the flights and hotel bookings are not perceived as a barrier anymore.

“If they do not travel to Japan this time, they can go another time without much hassle to arrange again,” he added.

Kiatkawsin said he does not expect the prediction will affect Japan’s overall travel outlook, given that the prediction is restricted to the month of July.

— CNBC’s Kaela Ling contributed to this story.