A Japanese city has a problem with graffiti, but not the type of spray-can graffiti on . It is graffiti in sand. Officials in Tottori City are asking to stop writing messages and drawing on its giant sand dunes. They said the graffiti damages the dunes and ruins the others get in looking at the sand. There were more than 3,300 of 'sand graffiti' at the tourist in the last . A newspaper said there were more than 200 cases year. In January, two tourists were ordered to erase a 25-metre-long birthday .
Tottori's sand dunes are all over Japan for their natural . They are Japan's largest and longest dunes. The dune is 50 metres high. They stretch for 16 kilometres along a geo-coastal park on the Sea of Japan. Tottori officials want tourists to understand how the dunes are. They will put more up to ask people to respect the dunes. The are worried whether or not tourists will follow the . They said: "We want to continue to protect of the beautiful sand dunes." More tourists are visiting the each year.