An oily substance was found splattered at Nijo Castle, a World Heritage site in Kyoto, and at a shrine in Nara Prefecture.

Officials who manage Nijo Castle, built in 1603 as the Kyoto residence of Tokugawa Ieyasu, said they found oil stains at some 20 locations in the castle, including the corridor of the Ninomaru Palace, on Feb. 12.

According to the officials, experts say the machine oil stains can be removed. Around 2,300 people visited the castle that day, they said.

The castle plans to hire guards to prevent similar incidents.

Meanwhile, police said they found oil stains Sunday at Asukaniimasu Shrine in Asuka, Nara Prefecture.

Similar incidents have been reported at Hasedera Temple in Sakurai and Okadera, Asukadera and Tachibanadera temples in Asuka, the police said. They believe the incidents are related.

The police are supervising officials at Todaiji Temple, a World Heritage site in Nara, to check whether their security cameras are working properly and to watch out for suspicious acts.