Is it possible to stay 100% in Japan

So next year I'm going to study aborad in japan but I'm a bit worried because I'm vegan. I'm veagn for health reasons so I feel like my host family won't think it's stupid because it's honestly the truth. But the thing is will I starve? I hear its impossible to stay vegan in japan and that I should change to being a vegetarian while I'm over there but I've been a vegan for 3years all ready and after my studies I plan to leave there for a year at least but is it really? Is it truly impossible to keep up with a vegan diet in japan?

It's not impossible. I know a few vegans and it's not as hard as you think.

Make a list of ingredients/foods you can't eat, try to translate them to Japanese and see if your placement program can pass along that info to your host family.

I'm a vegetarian living in Japan and it's easier than I thought because I cook most of my meals at home. I know some vegans here who have maintained their vegan diets however it can get difficult especially when they dine out. Sometimes we spend ages trying to find a suitable restaurant, and even then they have to request the chef to make special changes which is frowned upon in Japan. Luckily curry is quite popular here. There are some social situations when it's a little awkward for them especially if they are visiting someone's home or going to a Japanese style restaurant where the menu choices for vegans are severely lacking. As long as you're prepared to explain yourself in Japanese, and aren't shy about asking for special changes and the strange looks you may get as a result of this, you will be okay.

it will be very difficult unless you find a vegan host family.

Curry is popular, yes, but the base is usually made using meat-based stock in restaurants and eateries.

I hope you find a host family that is used to cooking Macrobiotics or used to cooking for family members suffering food allergy, because they would have a better understanding about special diet. Meanwhile, you can insist on cooking all your meals by yourself.

If you are going to stay with a Japanese host family, I don't know if you are going through a host family organization or school exchange, I would suggest asking the organizer to be sure to inform the host family about your dietary requirements and make sure that they are OK with it, or that they are OK with you using the kitchen to cook your every meal.

the word "host family" in Japanese sounds like a voluntary acceptance of you as a temporary family member. in general, they don't expect you are a vegan, because vegans are very few among Japanese. you will be expected and treated to be an ordinary Japanese. I think you should find a "special" host family who understand your situation. or, you rent an apartment and cook by yourself.
I understand the word "family" means the members eat the same food at the same time.

Yes, please take responsibility yourself and don't expect a host family to prepare different food for you from the rest of the family - whether it's vegan or vegetarian.

As others have pointed out, unless you have already CLEARLY informed either the host family directly (or the organisation planning the home stay for you) that you are vegan, you simply CANNOT expect to turn up and find them prepared for this. It will be a MAJOR imposition on the family and it can only end badly for all concerned.

If the family already know and have agreed to host you, then of course they know what to expect and it should be ok.

I understand the word "family" means the members eat the same food at the same time.

Not if you have health reasons like the OP does. Japan has a fair share of family members with health issues such as allergy, diabetes and various differences, so you're not alone :)

But I agree that, like everyone else, one of your first steps to adulthood is to be responsible for yourself.