Bookin stay in advance?

I have been planing a trip for me and 3 other friends to japan in the start of october.
I have done a lot of research and found that the second monday of october is a public holliday, so i know i should book the days befor and one day after in advance, just in case, but i cant find any recent information on the subject of booking hotells while traveling? We are going to stay cheap for the most part, so hostels, casules, manga cafès, love hotells and dormatorys. One exception is we are staying at a ryokan for one night, but that will be pre booked. Will booking on the go be ok?

Why don't you book them now and then cancel them if you're not going to use them? I sometimes book a hotel for a night about 6 months out just in case I need it. As my itinerary and plans iron out, I either leave the reservation and use it or cancel it as quickly as possible and always within the time before I get penalized.

If you book on the fly, you'll learn that many places are already taken or that the rate has skyrocketed from what you once thought.

The popular booking apps/websites will work on the go.

You'll have less choice, and you might miss out on cheap advance deals, but you should find something.

Why not test this out? Go to your favourite booking website/app and look for a room tonight, or tomorrow in a specific location in Japan. Then search for the same location, but move the dates a month or two into the future...