There are not many restaurants in Japan specifically geared toward vegetarians. However, for many centuries it was rare to eat animal products other than fish, and there are many dishes that vegetarians can enjoy.
Shojin ryori (temple cuisine) is vegetarian, but please note that some restaurants prepare dishes using fish-based broth. For details, checking with the restaurant in advance is recommended.
Eating meat became more common in Japan in 1868, when the days of the samurai came to an end and a Western diet became more widespread.
In Japan, shojin ryori cuisine made without animals products developed during the Nara Period (710 - 794) due to the influence of Buddhism. There is also kaiseki, traditional Japanese haute cuisine, which incorporates fish and shellfish.
As awareness of animal rights spread to Japan from Europe and the United States in the 1970s, the idea of avoiding a meat-based diet also spread in Japan.