A Japanese city has a graffiti problem. Not spray-can on walls graffiti, but graffiti in sand. City officials are asking tourists to stop writing messages and drawing pictures on the city's sand dunes. Graffiti damages the dunes. It ruins the pleasure people get in looking at them. There were more than 3,300 cases of 'sand graffiti' at the tourist hotspot in the past ten years. In January, two tourists had to erase a 25-metre-long birthday message.

The Tottori sand dunes are famous across Japan for their beauty. They are Japan's largest and longest dunes. The biggest is 50 metres high. They are 16 kilometres long. They are part of a scenic coastal park on the Sea of Japan. Tottori officials will put signs up to ask people to respect the dunes. The officials are worried tourists will not follow the rules. They said: "We want to continue to protect views of the beautiful sand dunes."