助けて (tasukete) = HELP
Just call this out and (hopefully) someone will come to your aid. (Most Japanese will also understand the word HELP.)

Police: dial 110

Fire / Ambulance: dial 119

Japan Helpline: 0120 461 997 toll free (for emergency advice in English 24 hrs)

 

JNTO has this site on what to do during/after an earthquake.

Point-to-use English >>Japanese emergency phrases pdf available here (courtesy of Hokkaido Tourism).

Google translate: https://translate.google.com/     (Useful for translating key words & simple sentences. Smartphone app also available for free download, with both verbal and written inputs/outputs.)

Tokyo Metropolitan Medical Institution Information You can search for the locations and services of medical institutions in Tokyo.

AMDA International Medical Information Center  AMDA is an organization offering medical information to foreign residents in Japan in their native languages. Telephone interpretation services are available for the following languages: English, Spanish, Portuguese, Korean, Chinese, Tagalog and Thai.

 

Embassy emergency contacts: (click the link to go to the embassy website)

USA: If you are an American citizen with a serious emergency, call the Embassy at 03-3224-5000.

UK: To report an Emergency involving a British National, please call 03-5211-1100 at any time.

Australia: 24-hour Consular Emergency Centre 03-5232-4101.

Canada: (03) 5412-6200 For emergency consular assistance, call the embassy of Canada in Tokyo and follow the instructions.