Pocket Wi-Fi in Japan

Our plane tickets have been bought, and our trip to Japan in November is becoming more and more real! Time to start obsessing over Japan travel tips!! @_@ One major tip, that wasn't really something I came across when last there 4 years ago, is pocket wi-fi. I am encountering this everywhere. So, let's find out about pocket Wifi and what it costs and where to get it!
I started out with this guide, which was pretty straight forward in answering some of my major questions.

I dunno, I'm not attached to my phone like SOME PEOPLE, and can get by looking up my routes in the morning at the hostels and making my itinerary in advance. I'm there to experience things without constantly updating my Facebook friends or Instagram. BUT, there are people who are really good at staying connected and draw their inspiration from being social. For me, I can get by with my super slow data from T-Mobile (which is apparently a slow 3G in Japan), but if you need access to maps and social media, then pocket wifi may be for you.