Subway operator Tokyo Metro plans to check signs at stations on its eight lines after a sign fell four meters to the ground at Nakano-Sakaue Station on the Marunouchi line last Tuesday.

The acrylic sign, which weighs just over six kilograms, suddenly fell onto the sidewalk at around 5:30 p.m. because of loosened bolts, Tokyo Metro said. No one was hurt.

According to Tokyo Metro, the sign was put up 16 years ago, and has been checked every year to prevent this kind of accident, NHK reported Thursday. No problem was found with the bolts when it was checked last December.

© Japan Today