'Kaisen don' in Japanese is a combination of the words 'seafood' (kaisen 海鮮）and 'rice bowl' (donburi 丼). Thus, 'kaisen don' is a seafood rice bowl. To be more specific, kaisen don usually consists of pieces of a variety of fresh (raw) seafood over a bed of unseasoned white rice. It's basically a bowl of sashimi on rice.

There is a lot of variety when it comes to kaisen don, but most kaisen don will be served with soy sauce and wasabi. Some people like to pour the soy sauce over the entire bowl before eating, while others prefer to dip each piece of sashimi into the soy sauce as they eat. There are no rules, so do whatever you please!

There's another kind of seafood bowl you might have heard of called 'chirashi sushi.' Chirashi sushi is quite similar to kaisen don, except that the rice in chirashi sushi is vinegared, just like sushi rice. Chirashi sushi, then, could be described as a kind of deconstructed sushi.

Sashimi, on the other hand, is simply slices of raw fish and other seafood, served by itself.

Chirashi don, sashimi don, bara chirashi, kaisendon... There are a lot of seemingly similar dishes out there. So what's the difference? Here's a quick breakdown:

-Kaisen don: a bowl of seafood over plain rice
-Chirashi sushi / chirashi don: a bowl or lacquerware box of seafood over shari (vinegared sushi rice)
-Bara sushi / bara chirashi: The same thing as chirashi sushi, except that the seafood is chopped into smaller pieces that are mixed into the rice before eating.

If you're looking for some of the best places in Japan to get awesome kaisen don, check out this article of restaurants serving "overflowing" kaisen don!