Granted, but Modern anything will often reflect a more meat based diet due to convenience (Lawson's bentos and snacks are amazing!) and despite several lost generations and the rise of the freeta generation(s) an over all higher standard of living as made meat consumption a norm rater tan an exception.
As a fomer cook/chef I can assure I can easily make 5 days our of 7 wit just tasty vegetarian meals rather easily because Japanese is my repertoire, and plant based dashi can be just as good as it's fish based variants (I onsider it a meat protein, albeit a more naturally sustainable one wen done properly/seasonally) thus can build flavour tat way.
By contrast I ave a harder time to do so with Italian which is my other cuisine despite having a more immersed culture experience--I lived and worked in Emilia Romagna wit its abundance of meat based parma options.
The modern Japanese diet is very, very far from vegetarian. In fact, you'll have a very hard time eating in restaurants if you're a vegetarian in Japan. I guess if you consider fish to somehow be "not an animal", though, it's much easier.