See here for a comprehensive list of types of fish.

To learn how to explain what you can and cannot eat in Japanese, see the What To Say section.

The word Ekisu (extract) is found after the animal products listed above in a surprisingly large range of product ingredients. I've found meat extracts listed on plain potato chip packs! It's possible that some of the "extracts" are not extracts at all but artificial flavours. Of course, the word ekisu isn't always a warning sign, as it's also found after a lot of non-animal food such as;
shiitake 椎茸, しいたけ, シイタケ
konbu (kelp seaweed) 昆布, こんぶ
yasai (vegetable) 野菜
gārikku, ninniku (garlic) ガーリック, ニンニク
daizu (soy) 大豆
onion オニオン

Katsuobushi (dried bonito) is the biggest nightmare for vegetarians and vegans in Japan. It, or katsuoekisu (bonito extract) turns up in soups, sauces, dressings and all kinds of products. Katsuobushi is also sprinkled on salads, tofu, okonomiyaki and other things when you don't expect it.

Bacon and ham turns up in a lot of unexpected places, particulary pasta, salad and bread products. The menu often won't mention that bacon is contained in the dish so you often need to ask.

Jako and Shirasu are tiny fish often used as seasoning and people often forgot that vegetarians cannot eat them. Watch out for thousands of tiny eyes looking at you from salads, pasta, tofu, hijiki and hidden in unexpected places.

Shortening is commonly found in bread products, cakes, desserts, cookies and sweets. Unfortunately, the source of the shortening is almost never mentioned. Shortening is often made with butter, lard, margarine or hydrogenated vegetable oil. Even if vegetarian, it is well known that trans fats are harmful to our health.

Gelatine turns up in desserts, yoghurt and the like as it does in every country. Though, one good thing in Japan is that sometimes kanten (made from seaweed) or konnyaku (made from a kind of yam) is used to make things gelatinous.

CONVENIENCE STORES
If you want something small to eat, then you can pop in at one of those ubiquitous convenience stores. They usually have a range of bentos and snack foods. For vegetarians though, it's limited to onigiri (umeboshi, konbu, sometimes there are other seaweed/pickle varieties), sometimes sandwiches, salads, pickles and bread products. Check the ingredients though. Of course there are also lots of snack foods and desserts which are ok.

SUPERMARKETS
Supermarkets usually have some ready-to-eat food. You'll probably be able to find onigiri, sushi, tempura, salads, sandwiches, pre-cooked rice, pastry and bread products, fresh fruit, fried food and other items. Just wander around checking the ingredients. Supermarkets often even provide a microwave to heat things up.

DEPARTMENT STORES
If you're near a major train station, head to the basement of a large department store such as Takashimaya, Mitsukoshi, Matsuya, Isetan, Tokyu etc. There will be lots of tiny food shops perfect for grabbing a ready-made meal. Look for the bakeries, onigiri, salad, tempura and tofu shops in particular.

BAKERIES
For a bigger range of better quality bread and pastry products which taste much nicer and have less artificial and animal ingredients, avoid the convenience stores and supermarkets, and head straight to one of the small or European-style bakeries. Of course plain bread and sweet foods can be found, but also savoury bread products and sometimes sandwiches. A knowledge of katakana will help avoid unwanted ham surprises. Japanese style bread tends to be very soft, a bit sweet and almost always white. Japanese bread products sometimes contain shortening which could be made from animal fat.

BENTO SHOPS
Bentos are ready-cooked or made-to-order meals available from bento shops like Hokka Hokka Tei, Origin Bento, and independent shops. Usually all bentos are not suitable for vegetarians, but these shops also often sell onigiri, salads, tofu and self-serve dishes which are sometimes ok for vegetarians.

SUSHI SHOPS OR DANGO SHOPS
You can get inari, kappa-maki, kanpiyo-maki, natto-maki etc from small take-out sushi shops. Dango shops are small shops which sell Japanese sweets made from rice and beans. Often there is a small take-away counter which sells sweets as well as some kinds of sushi.