For buying harder to get gear you might want to look further south to Okinawa. It’s Japan’s premiere destination for diving. Naha airport on the main island is about 2.5hrs flight from Haneda, with short connecting flights to Ishigaki (ferry to Yonaguni), and Miyako Jima.
Tanks are pretty easy to buy in Okinawa, particularly on fb groups (may/June and Oct/nov are the best time because that’s when the most US military members’ assignments end and they’re leaving island). There is no shortage of places that will do vis or hydro on island. You can also purge them and fly them back to mainland in your checked baggage. Be sure to check before hand with your local dive shop to see if they can get filled.
The diving in Oki is world class so perhaps a couple celebratory weekend trips are in order?
I’ve only dived Izu in mainland but it was pretty great. I’m hoping to get up there and go again this spring before typhoon season.
I only own my own tanks so I can dive once Wednesdays when my dive shop is closed, and a pony bottle as a second air source for solo diving. All my tanks are DIN annd I use the threaded adapter plugs to get them filled. That said, Japanese divers and shops almost exclusively use yoke, so get an adapter. I’m typically renting tanks though and using those tanks if I want to dive on Wednesday when my shop is closed. I’ve not heard of people storing their tanks at the dive center.
You can ride the train from Tokyo to Izu. The public transportation around Tokyo is pretty good. Lugging dive gear is going to be another thing though, but you can haul stuff around on the train in Japan. It’s a really common way for people to travel, but make sure you’ve got a decent roller bag because you’re going to be transferring trains a bit.
Personally if I were moving to Tokyo, I’d get a scooter or a kei car (yellow plate, road tax costs like 1/4 as much as a car with a full sized engine) just in general. Probably leaning towards scooter.
www.scubadiving.com
