Arva is a beacon brand made by Nic-Impex out of France and has a ton of backcountry pedigree. I have an Arva Evolution that I used for years. It is a great beacon. Unfortunately it is over 5 years old and has some issues that no longer make it worthy of backcountry use. It's still great for throwing in a pack and doing S&R drills. Regardless they make solid gear. I got to play with their 3 antenna beacon from a couple of years ago and it was very nice.
The Tracker DTS is the old standard. It's a two antenna beacon. As mentioned above, you want a 3 antenna beacon. It limits the spikes making pinpointing a lot easier, and that is very important. The Tracker 2 is a three antenna beacon and after an initial glitch with the first release, is a great beacon. The problem they had was resolved with a software update.
The Pieps DSP is pretty much the standard for 3 antenna beacons. They came out with it first and have a great track record. It also has the best range when in receive. It's a solid beacon. It's also what I am currently using.
A 3 meter probe is a good idea for the snow pack in Japan. Deep burials are not uncommon.
For a shovel, make sure it's metal. BD, Voile, Nic-Impex all make quality shovels. I like shovels with extendable shafts and a pointed nose on the blade. Makes chopping ice a bit easier.
An Avalung is also a good item to have. I rock one. If you do get buried, and you manage to get it in your mouth, it'll make the wait more agonizing but you should be conscious when your buddies dig you out.
Airbags are also great. With an airbag pack, if you go for a ride, you probably won't be buried, at the very least a good portion of you will be above the snow and you'll be quickly retrieved. Xavier De La Rue survived a monster avalanche by deploying his airbag. They work and they work quite well. Expensive, but if you get caught in an avalanche, I'd bet you'd be willing to pay a mortgage for a house to have one in that instant. Pretty sure I'll be rocking one at some point this year.