Never drink alone. Always wait for the whole group to receive their drinks before touching yours. After that, feel free to drink at your own pace. This goes for alcoholic and non-alcoholic drinks alike.

Try to never pour your own drink. It is customary to allow others seated close to refill your glass from their bottle, communal bottles, or a tokkuri (sake bottle). You should reciprocate, assuming that you are drinking the same thing. As the night goes on, you may end up pouring your own drink sometimes. Do your best to make sure that those around you aren't pouring their own drinks, though.

When someone is filling your glass or sake cup, you can show courtesy and mindfulness by holding the glass with both hands and being attentive to their gesture of goodwill. Kochi is also very famous for their citizens' love of alcohol. Check out this page for some more information on Tosa sake.

Can't drink anymore? Simply have your glass filled full and stop drinking from it. Similar to how Americans may hang onto the same drink for hours to avoid drinking any further, this is the best way to stop drinking. Though your principal may try to get you to drink what you have so he can pour you another cup...maybe try switching to ordered drinks at that point.