It was super hard to be vegan in Japan, but not impossible. If anyone goes to Osaka you need to check out OKO Takoyaki, it's one of the coolest places I've ever been to and their food is some of the best I had in Japan. If you look hard enough, you'll find my name on a couple of the walls
I really want to visit Japan. I've been wanting ever since I was a little high school weebaboo. But ever since becoming vegan I had to put that dream aside. Thank you for giving me some hope.
Tbh I mostly just survived because I was vegetarian back then, I went vegan some time after I got back. You can definitely do it, just use happy cow and plan well. Also you can live on kombu and pickled plum onigiri from 7/11 lol.
Also if you get out to Kobe, you should visit a place called "Vegan Cafe Kiu." One of the best meals I had on the entire trip and the coziest cafe I've ever been in, pretty sure it's just a house.