I took a 3 week trip to Japan from January 21 from February 12. I didn't have an itinerary, exploring as I saw fit and moving on when the mood struck me. Through the trip, I stayed in Tokyo, Tanabechuo, Kyoto, Osaka, Hiroshima, and Nagasaki.

Purchases

I made several purchases before the trip:

Japan Rail Pass

The Japan Rail Pass (Green) is a Japan Rail (JR) pass that lets you ride most trains in Japan. My most "Japan specific" purchase that I would recommend to anyone. The (Green) designation means that it is business class (effectively), which means better seats and reservations. I bought the 21 day pass for $700.

You have to buy this pass outside of Japan! It is only available to tourist to Japan. Purchase it before you leave, activate it when you get there.
This pass lets you ride most intercity trains at no cost. Intracity trains probably are not covered, but they are around $2.
You can save a little money by NOT using the pass and instead buying the tickets at the station. You can also of course pay less if you take a slower train or a less desirable route. It is up to you to decide whether this is worth your time.
The pass is the ultimate in flexibility. Just walk up to any JR office and tell them where you want to end up. They book all connecting trains for you then and there. They book you on the next (could be in 5 minutes) train that will get you there as fast as possible. If you have the Green pass they also reserve a seat for you on almost all trains. It is just so easy. You don't need to read local maps, you don't need to plan ahead, just point on your phone where you want to end up.
I think I basically broke even, but you could go wild on this thing and take a JR trip every day. It is really unlimited.

Google Fi

Google Fi worked out normally. When I landed in Japan it told me that I would pay the standard $10/gig data rate and I believe $0.20/minute. Use your Wifi call if at all possible. Coverage seemed pretty good everywhere. Was able to use it on most of the high speed trains, spotty between Hiroshima and Nagasaki.

Tortuga Outbreaker

The Tortuga Outbreaker 35L was a altogether worthwhile purchase. Most compeling features is the ability to open it fully (not just from the top) like a conventional suitcase. You don't think about it, but not having to pack and unpack your backpack is a real time saver. I also thought the compartment for the laptop with easy access was convenient, as you will be taking that out on a regular basis throughout the day.

Other feature true of the 35L is that it counts as cary on in all airlines (even small planes). It is convenient not having to wait for any lugage after a long day of travel.

hostelworld.com

I used hostelworld.com. Easy to use website. Clean interface. I would book my next hostel 5 days before actually arriving. Never had a single issue. They take I think like 10% as deposit on booking, you then pay the rest upon arrival at the hostel.

Bose QuietComfort 35

I recently bought some Bose QuietComfort 35 headphones for work. This is my best product purchase of 2016. They made air travel more pleasant (shut that baby up!). They made watching the landscape flow by on the trains more moody. They gave me a slight taste of home when I am feeling a bit lonely. Seriously. Great. Headphones.