Information on hikes in Japanese Alps

Hi,

I am looking into doing a 4 days hike (or maybe more) in the Japanese Alps and I found it very difficult to gather information :/
This would be end of August, or beginning of September.

My main goal was to go through the Takama gahara onsen.
Then from there, I was just thinking of filling up with different variants but I have a hard time to really figure out long are the hikes and where there are trails. I guess this is related, I cannot find a proper map online about trails and/or clear distance/elevation. I'm not in Japan yet so I cannot buy the map in a bookshop yet (will do as soon as I get there).

First off, are there any special dates I should be careful about? Like some bank holidays where everything will be crazy full, or such?

Ok here are some itinerary ideas:
- bus from Tokyo to Toyama overnight that should arrive at 5am
- bus from Toyama to Oritate camping ground arriving around 7:30am
- from there, hiking through:

1. Taro summit, and taropei hut
2. in the valley, by Yakushazawa hut
3. Here, I found some hikers going up until Ununohira (?)
4. then going down towards takama gahara onsen and hut
=== Is that required to go up to Ununohira? Is is possible instead to stay closer to the valley floor to reduce the overall elevation?
5. Hike up to the east and pass Mt Suisho, Mt Washiba, Mt Mitsumata Renge until Sugoroki hut. Maybe do Sugoroku peak?

From there the short version is:
6. Go through Yumiori peak then down: Mihira sanso, Wasabi Heikoku, Shinhotaka ropeway and stop at Hotaka hotspring. From there, get a bus or something?

The long version that look very tempting:
6bis: From Sugoroki, go through Momisawagake and take the ridge East towards Yarigadake.
7. Follow up with Mt Nakadake, Mt Minamidake, Daikiretto, Mt Kita-Hodaka, Mt Hotaka.
8. Ideally I want to go through the next Ridge as well (only after that, it seems complicated to go back down to Kamikochi (I don't see any trails). This would be: Mt Ainodake, Nishihtakadake.
9. From there try to get down to kamikochi or shinhotakadake: I need to get to matsumoto somehow so I assume I'll find some buses.

I also had some ideas of starting by Mt Tsurugi then going South until Takama Gahara but it seems quite long and I will definitely not have time to keep going towards Kamikochi. And going to Matsumoto from Mt Tsurugi or Takama Gahara seems a bit of a hassle.

I know daikiretto and the ridge form Hotaka to Nishihotakadake are dangerous and will require significant amount of time to cross. And that I shouldn't attempt those by rain. In case the weather is not with me, I will just not go through them and find an alternative.

Do you know how I could estimate the distances, elevations and time I would require to cross those sections? Also, do you know how I could get to know the existing trails? Before I get to Japan and buy a map.

I found some wikiloc hikes doing the "short version". Where they take 4 days for it, but they seemed to have camped (which I won't do as this is too much equipment for me to bring by plane). I will stay in huts and hike light.

For the easy version the nights are in
1. Taropei hut
2. Takama Gahara
3. Sugoroki hut

For the longer version, I was thinking of maybe rushing through the first day to combine 1-4. So going straight to takama gahara.
Then second night next to yarigadake or minamidake?
Not sure about third night. I guess it would depend how far I could get with daikiretto.
Of course those are long days but there seems to be plenty huts so I could always stop earlier and skip part of the trail.

Thanks in advance for any information :)