Japanese is the main language spoken here. Japan is a very ethnically homogenous nation, meaning that the vast majority of people who live in Japan are native to the country. Students are often taught English in high school, but few people go on to become fluent. With that being said, when I would speak Japanese to people, they would sometimes respond to me with whatever English they knew, and we could manage to communicate while switching between both languages!
Yen. ¥100 is roughly equivalent to $1 U.S. dollar, so a quick way to convert currency is to just drop the last two numbers. For example, ¥1000 becomes $10, ¥10,000 becomes $100, and so on. Japan is a cash-based society, so many businesses will not accept debit cards, though some newer convenience stores and restaurants will take both. I was surprised to discover that coins are quite useful in Japan, with the largest coin being worth ¥500. You can often pay for a nice lunch with just a couple of coins from your pouch.
