The following are my observations from two weeks here, of similarites and differences between Japan and New Zealand. I have broken them down into things you should already know (the obvious), things you might know (the informed), things you may not know (the not so obvious), and quirks.
Things you should know
Japanese eat a lot of rice.
They use chopsticks to eat.
It is customary to remove footwear when entering an abode.
Things you might know
Japanese use hanko (personal stamps) in lieu of signatures.
Items in shops are taxed on top of the price shown -- the hyaku en (hundred yen) store puts a five percent surplus on items sold. This makes it the one hundred and five yen shop!
Things you may not know
Cars are divided into two types, yellow and white plates. Yellow plate cars have small engines and are more environmentally friendly and economic to run.
On offical forms, the date is given according to the current emperor. This year is the 20th year of the reign of Emperor Akihito, the 125th emperor of Japan who acceded the throne in 1989.
There is a daily chime here that goes off at 6am ("Get up!" Or in my case, "Haha, I have disturbed your much needed sleep. I hope that you are tired for the rest of the day because of this annoyingly loud and unnecessary noise so early in the morning."); at 12pm (lunch time, sure as clockwork); 5 or 6pm -- either it goes off at different times or I can't remember which time the early evening one is; and at 9pm -- for some weird reason ("We interrupt this programme to randomly chime! ding dong ding dong... ding dong ding dong.").
During Summer it gets dark really early. Japan does not have daylight savings, but it is still very early -- 7-7.30pm in the middle of Summer. The humidity is a given, but there is sudden, sporadic rain a lot of the time. I have learned to carry an umbrella on even the clearest of days.
The bug life here is amazing. The insects are huge: I've seen giant cockroaches, cicadas and hornets, and have heard that there are huge ants. At least the dragonflies are a normal size. I also saw a gigantic, brown spider (half the size of my palm). Mostly harmless, but I still wouldn't want to piss one off in the dark.
There are loud train station announcements. I don't know why they have to announce so much information to the entire town every time one of the infrequent services runs through. I know that at Wellington station there are announcements all the time, but that's nine platforms and it's important for commuters to know these things. Here, it just seems over-embellished to the point of being ridiculous. "Hey, all you people that live on the other side of town from the station; I hope that you can hear this announcement about what the train guards had for breakfast today and what their lucky lottos numbers are, because here it comes!"
I'll keep my eyes and ears open for other Jap-quirks and the like. ^^