Those are the Tottori Dunes, engraven by pranksters who quite possibly got mixed up by the phonetic similarity of "fu" and "hu" in Japanese transcription; the problem is, they very likely face legal action for doing so:

The Ministry of the Environment subsequently launched an investigation into their actions, on suspicion that they violated the Natural Parks Law.

The students, who participated in various outdoor activities, have reportedly apologized for marking the dunes.

"We weren't aware that we were acting illegally. Half of it was for fun, but it was careless," a member of the group was quoted as saying. 

Hey, the letters were only 50 meters long, eh? Who thought anyone would ever notice? Dingbats.