I'm planning a trip to Japan and I'd like to spend one week immerse in Japanese nature. I've read something about the "Daisetsuzan Grand Traverse", which is a 5 days and 55km trekking on a route that connects the Asahi-dake and the Tokachi-dake. I don't usually go for trekking in my home country, even if I enjoy doing it from time to time, so I'm wondering if anyone did that and can actually tell how difficult could be for someone who is not even an amateur trekker (I'm in not in a bad shape, tho). If you also have any other alternative route that you enjoyed feel free to share!
I'm not brilliantly positioned to answer this, but since nobody else has...
So I walked a small section of the route back in 2000 or so (Sounkyo Onsen to Kurodake and back) as a day trip, just enough to realize that it's a pretty "serious" national park and you'll want to be well prepared for a serious hike:
As you can see, the problem is not that it's 55 km long, it's that you're going up and down and up and down in the mountains, exposed to the wind, rain, snow and ice (there's no forest cover on the plateau) -- the picture above is the view from Kurodake on a relatively warm late summer day! So if you have no previous experience, I'd hook up with somebody else or try out a shorter section of the route. Asahidake to Kurodake can be done in two days with lodging en route, so you don't need to carry a tent etc.
This guide looks rather useful: http://www.idioimagers.org/Daisetsuzan-guide.htm
And for what it's worth, his opinion is that 5 days for the full traverse is pushing it, and most people are better off budgeting 6 or even 7.