I'm actually heading to Japan in 4 days for my second climb of Fuji. (yes, I'm the fool in the proverb you quoted
Did the route you did last time, this time I hope to do it from the Sengen shrine at the base and going down the Gotemba trail on the other side for a little new scenery.
Little worried after cutting my Langey to Whitney hike short last month, but I'm giving myself three days if needed and the altitude won't be as big of a factor. The mountain huts really help to lighten what you have to carry.
Plus I'm planning a 6 night trek through the northern Japan Alps. Again, the mountain huts will hopefully make that doable with only a 17 pound pack and elevations between 7,000 and 10,300. Being able to buy food and water and drinks along the way and having a warm futon to sleep in makes it quite a luxury.