Thanks for replying fast, guys
I guess it seems pretty hard with the equipment. From my point of view, I would prefer to rent rather than buy, since it's a one-day-trip. However, when traveling from the other side of the world, one is willing to pay a lot for cool experiences, and snowboarding Mt Fuji would definitely have been an amazing experience. So buying used equipment for one day might be okay, considering the pay-off!
Hard-Off seemed like an interesting option for buying gear, but I didn't find anything there in English? Unfortunately, I don't know too much Japanese. What I s