Perphekt,
Thank you so much for telling me that you are a vegetarian. I have to warn you that Japan isnt a vegetarian friendly contry. Some of my co-workers from the US were vegetarians and they had to stick to their guns about eating things the Japanese made. some of our Japanese friends would test them to see what they would eat and what they would not eat. Its not a concept that has wide spread acceptance. I dont know what type of vegetarian you may be but be aware that many of the soups are fish stock based. Also, Japan is in love with pork. Many things are pork flavored or have ham bits in them. If you eat a plain Okonomiyaki make sure that they dont put Bonito flakes on top as it is fish.
Here are some phrases to help you and any one else who may also be vegetarians
3nodding Watashi wa bejetarian desu - I'm a vegetarian (see note below)
Shojin ryori [show-zine ryo-ree] - vegetarian cuisine, usually Buddist style
Saishoku-shugi ryori wa arimasuka? - Do you have any vegetarian meals?
Shojin ryori wa yatte imasuka? - Do you serve vegetarian foods?
Watashi wa .. - insert one of the following words here)
o itadakimasen. (I don't eat ......)
1. niku (nee-koo) - meat
2. sakana (sa-kah-nah) - fish
3. tori (tor-ree) - chicken (or any type of poultry)
4. tamago (tah-mahgo) - egg
5. gyunyu (giu-new) - milk
6. nyu seihin (new say-hinn) - dairy products
Buta niku - pork
Gyu niku - beef
Tori niku - chicken
These literally mean "pig meat", "cow meat" and "chicken meat", respectively.
Nashi means without. So no meat would be
Niku nashi; Buta niku nashi; Gyu niku nashi; Tori niku nashi NOTE: for many people the English word "vegetarian" is already a familiar, well-known word; but in the rural areas or if you talk to an old person, please use the word "Saishoku shugisha" [sigh-shoh-koo shoo-gee-sha], a Japanese word for vegetarian. (Don't worry about this word if you are just visiting Tokyo -- just say "vegetarian".)
http://www.ivu.org/phrases/easia.html 
