Say you were given an opportunity to live in Japan – which city would be your go-to choice for climbing/hiking/general outdoor niceness, all in a reasonable travelling distance? Bonus points for access to sea cliff trad or adventurous mountain trad and warm weather (Hokkaido looks too cold and I am a wimp)
Will you be there long term? I spent 6 months living there - if in a similar situation the time of year you're going will have a big impact. I'll post more later on my experience of living in Tokyo and getting out climbing as much as possible.
So I spent 6 months living in Omiya just outside Tokyo from December to June. Obviously climbing centres are everywhere and they're generally excellent. The place I was living was probably 99%+ Japanese, basically no tourists or ex-pats and the scene at the local wall was really welcoming and friendly.
In terms of climbing outdoors, I found a crew of ex-pats, mostly Americans, but various other nationalities as well, within my first week by joining facebook groups for local climbing scene and posting on the Reddit climbing page.
If you're working a 9 to 5 getting climbing outdoors in the week is basically impossible as even in the summer it's dark by about 7 pm. On the weekends getting to spots to go climbing is pretty easy thanks to the amazing train network. From Tokyo there's a number of decent crags within about 2 hours train, usually followed by a short walk. Be sure to look up Onsens in the area, there will often be one very close to the climbing (they're everywhere) and it's a fantastic way to relax after a day's climbing.
In general I found trad climbing quite hard to find - the Japanese tend to try and sanitise the outdoors quite a lot and this means lots of bolted routes. For example in the mountains you'll often find a chain or railing to help you up a steep rocky section. That said, there is often the odd trad line at the sport crags, and there are some good areas to visit for a weekend. The major one is Ogawayama (you probably already know this if you've done much research), but unfortunately I was there in the wrong season to check it out.
Towards the end of my trip I did manage a weekend doing an alpine rock route at Ichinokurasawa, highly recommended. This is the route I did, and I found this website to be a pretty handy resourse: https://climbjapan.blogspot.com/2009/02/route-name-south-ridge-nanryo-mountain.html.
I also spent many weekends hiking into the mountains and staying in huts, there is generally a really good network of huts in the mountains ranging from wooden shacks to alpine huts with heating and hot meals and beer. I mostly went to the Japanese alps in Gunma and Niigata prefectures. Again, I found ex-pats with local knowledge to go with via facebook etc. Also check out OCJ (Outdoor Club Japan), they have a wierd old-school forum and an inactive facebook page, but a friend I made out there was organising a lot of trips through the site that were always good fun; unfortunately I think he's leaving Japan soon.
Sorry this post is a bit of a mess, just some scattered thoughts, will update if I think of anything else.
Near Tokyo my favorite mountain day trip was Mt Myogi. Not alpine, but a good introduction to caldera mountain climbing with chains (and with monkey's).
Mt Asama is also an interesting hike and easy to get to, although climbing wise the rock was extremely suspect around there. If you camp, be mindful of bears.
This was a really interesting, thanks so much for sharing your experience of it! It's given me some good places to look into so I really appreciate it. Good to know you found it pretty easy to find people to climb with online, that was something as I was a little worried about.
Shame about the trad climbing though, I'm guessing i'll be luckier with trying to scout out sea cliffs for trad. Although I don't even know about the feasibility of taking a rack so perhaps it's not such a bad thing.
There's an area called jogasaki that has some sea cliff climbing, I never made it there and expect it's mostly sport but there's probably some trad.
Most important thing is probably to try and find a climbing partner who has reasonable Japanese as it's really hard to find info in English about climbing there.