I'm visiting Japan in late May, early June, and I hope to go skiing. Mount Gassan (月山, literally "moon mountain") in Yamagata prefecture seems to be my best bet - it has a ski season of April to July, with the season opening determined not by when they first get snow, but when they can get rid of enough of it to open up the roads!
I asked the tourism information office of Mount Gassan, and they said that ski rental isn't available in Gassan itself. Are there other locations at which ski rental is available?
I anticipate going by shinkansen to Yamagata city, and hiring a car from there, so something in Yamagata city, or between Yamagata city and Gassan would be ideal.
As a fallback, I guess I could try hiring at Zao Onsen, but that's in the opposite direction from Yamagata city as Gassan is!