I'm vegetarian in japanese.

dashi ( it's the soup base ) 

“Niku to gyuu to sakana to  basashi to tori tabemasen.” 

(“I don’t eat meat, cow, fish, horse or chicken.”)

Watashi wa bejetarian desu - I'm a vegetarian

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 ......)

niku (nee-koo) - meat

sakana (sa-kah-nah) - fish

tori (tor-ree) - chicken (or any type of poultry)

tamago (tah-margo) - egg

gyunyu (giu-new) - milk

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".)