July and August are prime climbing season for hiking to the top of Mt. Fuji, Japan’s highest mountain. From Wikitravel.org:

The thing to do on Mt. Fuji is, of course, to climb it, preferably overnight so you can reach the top in time to see the sunrise (go-raiko). As the Japanese say, a wise man climbs Fuji once, and a fool twice, but the true wisdom of this phrase is usually only learned the hard way. Depending on your pace, the climb up will take 5 to 8 hours, and the descent another 3 to 4.

Oh, and here’s the cool part:

Once at the top, you will pass under a small torii gate and encounter a group of huts selling drinks and souvenirs; this being Japan, you will even find vending machines on the top of Mount Fuji. Yes, this is as anticlimactic as it sounds, but with any luck seeing the sunrise above the clouds will make up for it. You can also gaze into the long-dormant crater at the center of the mountain. Strictly speaking, this is not the highest point of the mountain; that honor goes to the meteorological station on the other side of the crater, an additional 30 minutes hike away and not really worth the trouble. A full circuit of the crater takes around an hour.

Here’s one guy’s hike writeup — a mere 5300 feet of elevation gain to the summit near 12,400 feet.

Just before daybreak, you could see the sky starting to lighten up in the north, then in the northeast. (For the whole night, we could see the lights of towns in the valleys below us; and the dim glow of clouds 40 miles to the northeast, lit up by the distant lights of Tokyo and Yokohama. But not lit up quite enough for hiking without a light.) IF it were perfectly clear, you could probably see the skyscrapers of Tokyo, but we don’t expect that very often in the summer.

The books all say that the busy, popular climbing season is in July and August – especially in the vacation time of August – but they neglect to mention that this is also the rainy season. If you got started up and got a LOT of rain, that would not be much fun. I don’t know your opinions on hiking in rain, but I don’t find it fun at all. Hiking up Fuji in the rain – well – you know what they say about owning a yacht: like standing in a cold shower, tearing up thousand-dollar bills… Same darned kind of no-fun. If you happened to be in Japan in June, you might avoid the chances of rain and most of the crowds. Or in September. But then the huts would not be open. Still, for a long day hike, (well, NIGHT-hike) it is NOT that big a deal to carry your water and munchies.

If I ever make to Japan, Fuji is on my itinerary.