I was charged for otoshi, which I didn’t expect.

Sometimes in Japan at an izakaya or similar restaurant, each person is served a small dish of food before any order is placed. That is called otoshi, and you will be charged for it. It is best to consider the otoshi a table charge. It is part of the culture of the Japanese izakaya. If you are actually brought food that you didn’t order, check with the serving staff about the dish when they hand it to you.