“We will be temporarily closed today as we are unable to adequately ensure the safety of our customers, performers, and on-site staff at this time,” the Sanrio Puroland park said on its website.

Hello Kitty, created Sanrio Co and celebrating its 50th anniversary this year, is one of Japan best known cartoon characters. The mouthless cat-like figure, used to market everything from plush toys to aircraft, has been deployed by Japan’s government to promote tourism and as an ambassador of cute.

Police, who investigated the theme park after it received the e-mail warning, did not find any suspicious objects, public broadcaster NHK reported, without citing any source for its information.