There has been a series of incidents in which pillars, gates and other property at six locations including temples and shrines across Tokyo, Kyoto, Nara and Okinawa prefectures in Japan have been vandalized with an oil-like liquid.

There was a similar series of occurrences in 2015.

A special squad of the Metropolitan Police Department is conducting a full-scale probe on the theory that the perpetrator could be a copycat criminal who is imitating the incidents from two years ago.

On April 3 the Cultural Affairs Agency required prefectural boards of education to take thorough measures to prevent crimes against cultural assets. Temples and shrines have since been on higher alert.

An odorless, adhesive liquid was found splashed on a torii gateway arch and other structures at Meiji Jingu shrine in Shibuya ward, Tokyo, on April 3. This was just after the shrine increased the number of officials on patrol within its precincts due to similar damage found two days earlier at Shimogamo Shrine in Kyoto and Kinpusenji temple in Yoshino, Nara prefecture — both World Heritage sites.

A source at Meiji Jingu shrine expressed disappointment: “We regret that free access to the precincts has likely been abused.”

Similar vandalism was confirmed at Zojoji temple in Minato Ward, Tokyo, on April 4. The MPD strongly believes the same perpetrator is behind the series of incidents.

In November last year in Nara Prefecture, there were three cases in which liquid was found splashed on cultural assets, including a Buddhist statue designated as a national treasure.

Security cameras at Kofukuji temple in Nara recorded three people who appeared to splash the liquid onto the assets.

Liquid believed to be fragrant botanical oil was found on property at 48 shrines and temples in Tokyo and 15 other prefectures in 2015.

Katori Jingu shrine in Katori, Chiba Prefecture, was among the cases. The Chiba prefectural police obtained an arrest warrant for a 54-year-old Japanese man living in the United States on suspicion of damaging a building. The man left Japan for the United States after the incident and has not been arrested.

It is said that the man, a founder of a religious organization, told a gathering: “Shrines are nests for evil spirits. I purified them by spraying oils.”

The police believe the man did not commit the recent series of incidents because there are no records indicating he has reentered Japan since the incident at Katori Shrine.

The police considered the possibility that the recent incidents could have been committed by someone copying those from two years ago and are analyzing the splattered liquid.

The damage is serious for the temples and shrines, which see a large number of tourists.

Kinpusenji temple has suffered two incidents. After the first one, the temple sought the help of experts, who removed the offending substance by using special solvents to lift the liquid that had seeped into the wood.

The Cultural Affairs Agency said such removal work costs hundreds of thousands of yen.

Shurijo Castle Park in Naha is among the locations to have suffered damage in the recent series of incidents. A bronze bell with liquid splashed on it was removed from public display.

Temples and shrines are also strengthening their own security measures.

Shinkoin temple in Minato Ward, Tokyo, set up seven security cameras after its assets were doused with liquid in 2015.

The master of the temple said the damage at Meiji Jingu shrine, Zojoji temple and others could also occur at other locations.

Officials at Shibamata Taishakuten temple in Katsushika Ward, Tokyo, have delayed the time they finish work so they can patrol the precincts. The MPD’s Kameari Police Station has also reinforced patrols in the area.