When you come to Japan and go drinking with Japanese people, some of them will say, “Let’s start with beer!” and then you’ll all give a toast. If you want to behave like the Japanese, you'll need to pour for other people, even when you are not a host or a hostess. This is a kind of Japanese tradition, and how Japanese people communicate each other while drinking.The legal drinking age is twenty years old here. When there are unmarried young women, you should look after their glasses carefully, because a woman can’t pour for herself. If an unmarried young woman pours for herself, it is said that she will not be able to get married. So a woman has to wait until someone notices her glass. If a woman wants to be poured, she pours for someone, and then the person will notice her empty glass and pour for her.
Is this too much of a bother? Perhaps, but if you are a man, I think this could be a good excuse to speak to a young woman who you like. Good luck!
P.S. If you have questions about my post or Japanese customs, don't hesitate to ask.