If you're a fan of Japanese martial arts styles and want to learn more, there's a wiki that's a gold mine for you. Gottsupedia, as it's known, is a repository of Japanese martial arts – especially aikido – along with their histories and specific techniques.
Yoshinkan's emphasis on basics and instilling them in students through repeated drills is a direct product of the difficulties encountered when Yoshinkan first began teaching exceptionally large groups, such the Tokyo police. … Ueshiba did not give exact instruction, instead he would show a technique and let everyone figure it out saying "That's fine, that's fine" to everyone's way of doing it.
The entire wiki is the work of just one guy, so there's not much yet in the way of collaborative editing or fact-checking, but the 193 articles on hand show that the one dude is pretty serious about his stuff.
You probably won't get in a fight in Japan
But you should know what to do if you meet the Japanese police. Read the Guide to Police in Japan.