"Nomikai" are drinking parties where you enjoy alcoholic drinks with your peers. You may be invited to one of these parties during your stay in Japan. These are rather casual gatherings, but they have their own characteristic customs and set of manners. Let's have a look at a few main points!
Izakayas are a type of Japanese-style pub that often become the venue for drinking parties. They offer alcoholic drinks and simple dishes to go with them. There are two types of izakaya: in one of them you have to take your shoes off at the entrance or right after entering the place, and in the other type you can go in with your shoes. In the former, a member of the staff will inform you that you need to remove your shoes, so you should follow their instructions.
Especially in the former kind of izakayas, when they are formal Japanese restaurants, the staff will take care of your shoes and put them away, and bring them back to the "doma" (the place where you removed them) when you are leaving. On the other hand, more casual izakayas feature a system in which you are expected to put your shoes in a locker and lock it yourself.
You should also pay attention when choosing where to sit after the staff takes you to your table. Usually, in Japan, the etiquette is that persons of a higher rank (older or with a higher position than yours) sit at the "kamiza" (seat of honor), while younger people or people in lower positions sit at the "shimoza" (lower seat). It is a little bit hard to define which seats are "kamiza" and "shimoza" but, as a general rule, kamiza is the furthest seat from the entrance, and shimoza is the closest seat to the entrance. If you are in a private room within the izakaya, the kamiza will be the furthest seat from the door (or the paper door, in the case of a Japanese-style room). If the people that you are going to drink with are your superiors, pay extra care to where you sit.
In Japanese drinking parties and banquets, the etiquette is to not start drinking or eating until all members of the party have been served their respective drinks and "otooshi" (appetizers). Usually, the flow before a drinking party starts goes like this: first of all, all participants order their drinks, and after they all receive their drinks and toast, they order the food. The staff will also ask for your drink order only in the beginning.
Remember that, even if a reservation has been made in advance for the meal course, you will have to wait until everybody has their drink and you have toasted before you can start eating.
"Oshaku" is a Japanese custom that consists in offering a drink and pouring another serving for those around you when their glass becomes empty during a drinking party or a banquet. If you are the one receiving "oshaku" and they offer you a bottle of beer or sake, you should hold your glass with both hands while the drink is being poured. It is considered rude to leave the glass on the table.
Generally, "oshaku" is something that younger or lower ranking people will do to people in a higher position, so if a superior pours a drink for you, do not forget to thank them.
Pouring a drink for yourself is called "tejaku". You should avoid doing this, as it is understood to mean that "those who are drinking with you are not paying attention, so you have to pour your drinks yourself". However, if you are drinking with close friends, you can casually say "I am sorry, but I am pouring this for myself" and drink at your own pace.
There is no need to force yourself to accept "oshaku", so if you think that you cannot drink anymore, you can refuse in a polite manner by saying "I think I will be stopping now" or drink just a mouthful and leave your glass on the table. If your glass is full, nobody will suggest that you drink more.
Even fun drinking parties come to an end. At the end, you will obviously need to pay the bill, but you need to be careful about this. In Japan, in general, there are a few different ways of settling the bill, namely "warikan" (in which the bill is split in equal parts), "keishahaibun" (in which the elder or higher ranking people pay more than the invited ones), and "ogori" (in which the elder or higher ranking people pay for the bill in full). Which method is used depends on each and every situation, so it is a good idea to at least show an intention to pay (take out your wallet, etc). It is rude to act like you take for granted that others will pay more or the whole bill. However, if you are with close friends, there is no problem with asking how much you should pay in a straightforward manner.
In Japan, where a lot of people are rather shy, banquets and drinking parties are invaluable occasions to deepen communication. This is one aspect of Japanese culture, so if somebody invites you along during your stay in Japan, make sure you do join them and enjoy.