I am an official Letterboxer. I signed up for Atlas Quest, username Shlaci, and found my first letterbox when I was in Tokyo with my in-laws. There are a few around Tokyo, and I printed out directions to all of them in case we went anywhere that had one. We visited the Imperial Gardens in Tokyo, and there is one letterbox there, the Lotus letterbox:
I used my signature stamp to mark that I was there, and stamped their lotus stamp into my logbook as the first stamp. Many people have a nice book, but I decided that since I may want to re-order mine by place and I want to be able to bring supplies with me on hikes like the Appalachian Trail (where weight is a big priority), I want a method of recording finds that doesn't take up much space. I got a small trading card holding binder that comes in a box. It's perfect for trips where weight isn't a problem, I put folded blank notecards into the slots and can write the name, date, and location of the box on the notecard. The box holds a small stamp pad and my stamp easily as well. When weight is an issue, I can take just a handful of notecards, a small stamp pad, and my stamp. The notecards can be rearranged and I can of course always get better trading card binders or notecard filing systems to keep track of my finds.
Later this month, I'll be traveling to Tokyo for the national RoboCon competition to cheer on our team. We have a few hours between the bus arriving in Tokyo and the start of the competition, so I'm going to see how many other letterboxes I can cross off my list while I'm there. I know I'll get the Tokyo Disney one when my family comes to visit, but there are a few others fairly close together near interesting sites or museums that I should be able to get.
Hopefully I'll be able to hit all the ones currently in Japan before I leave!