People, a minimum familiar with the Japanese culture, know that before drinking sake (or other alcohol), it is customary that one makes a small speech ending with the “Kampai!” In this context, “Kampai!” is almost always translated as "cheers!". But what does it really mean? In Japanese, Kampai is written 乾杯 in kanjis because the expression is of Chinese origin; similar terms exist in Mandarin (gan bei), Cantonese (gom bui) and Korean 건배 (geonbae). In the binomial jukugo 乾杯, 乾 means "dry" and 杯 stands for the sake cup. So, “bottoms up" would be a more literal translation than "Cheers". Of course, the expression “Kampai!” does not encourage anyone to empty their glass in one go. Except in cases where people toast with a shooter, I’ve never seen anyone empty his cup in one sip after saying “Kampai!”.
Besides, there is a ceremonial variant to honour the deceased at the funeral. It is pronounced Kempai and is written 献杯 (tribute), the first character meaning "offer or present". After the prayer, each one, bowing and raising his glass very little to present it towards the altar where the ashes rest, says: “Kempai!”. It's that, historically, sake was a sacred drink offered to the gods. This offering became part of the various Shinto rituals and sometimes even Buddhist ones. Festive toast is a more recent custom borrowed from the West. Be careful not to invert the two expressions.