Officials have no idea why the hand straps are going missing, but they count at least 400 have been removed from train cars in and around Tokyo since November, Japan's Kyodo News Service reports . The straps are difficult to remove and are apparently worthless, which leads investigators to suspect it is vandalism for its own sake, which is rare in Japan. "I have no idea what this person is going to use them for, but it causes trouble for our customers so I hope this person will stop doing this," one railway company spokesman said.