I hope this doesn’t happen to you Pushka, but something to consider - what is their official policy if they decide to “walk” you? By the sounds of things that you’ve reported across various resources, it’s possible a lot of people won’t budge and they may be forced to take more drastic action.
At a minimum, full refund of course. Anything beyond that is presumably at their discretion. But if you were involuntarily “walked”, you’re jeopardising the rest of your trip with relatively short notice to book accommodation with prices sky high all over Japan. And assuming you have sufficient travel Insurance coverage for cancellation etc, would you really want to still go with a different itinerary and mode of transport?