Russ Kaufman says: On Sunday we were in the Chiyoda-Marunouchi area of Tokyo. We went to a small typical Osaka-style Okonomiyaki (savory cabbage pancake) shop. Usually the only options in the past would be a seafood or meat option (or combination option—most popular are probably octopus or pork). Now it is common at these shops for an all-vegetable option on the menu. It’ s much easier than when I lived in Tokyo decades ago. Here’s the Tokyo Vegan Ramen Center. https://www.instagram.com/tokyo.vegan.ramen.center/?hl=en
The Tokyo vegan vegan and vegetarian restaurant guide should be helpful. https://www.gotokyo.org/book/en/list/5175/

Another member Steve said:
When I was in Japan way back in October-November 1987, a useful trick was to say “Shai shoku shugi shaa desu,” which roughly means “I am a Buddhist vegetarian.” If I just told them that I was a vegetarian then they didn’t take it seriously, but the Buddhist part made them believe that I was committed for religious reasons and therefore they shouldn’t sneak in something.

From our former intern Hiroko from japan
https://www.vrg.org/journal/vj2003issue3/2003_issue3_noodles.php
https://www.vrg.org/journal/vj99nov/1999_nov_japanese_holiday.php
https://www.vrg.org/journal/vj2001jul/2001_jul_kyoto.php
https://www.vrg.org/journal/vj2000may/2000_may_japanese_restaurant.php
https://www.vrg.org/journal/vj99sep/1999_sep_vegetarianism_japan.php
https://www.vrg.org/journal/vj99sep/1999_sep_shizuka_tsuruta.php