Oh my God,
I was in Japan last weekend. Unfortunately, I cannot give you much advice on your situation. I found it very hard to continue eating fruit, as it is really very expensive. I also found that only after two days, my digestion did slow down dramatically. The friends I visited tried to find me vegan food and did really the best they could, but still the lack of fresh produce was depressing.
Maybe a small tipp: I am doing finde on soba and vegan sushi, and some bloating goes away with drinking warm/hot water and/or herbal tea. Maybe try to find a farm around where you live and source your produce directly?
Wish you the best of luck for your situation!
If you're going to be in Japan a while, you should find out if they have community gardens and grow your own greens (and maybe some melons and berries). Do you speak japanese? Could you possibly get work helping produce farmers in your region (and taking produce as partial/full wages)? Perhaps if you were assisting a local grower, they could give you a little plot of land to grow food on. If you have any small outdoor/patio space, you can do raised container gardening, check out growingyourgreens on youtube for ideas.
If none of this will work, then you will have to be a cooked carb vegan and just eat the small amount of produce you can afford.
You could also take barley green or green magma whichever is cheapest in your area (dehydrated green barley powder with water), it has live enzymes. Everyone can also grow indoors sprouts for eating and wheat grass for juicing (and yes, it's gluten free with the most supercharged nutrition you can get in a glass, a little shot glass is sufficient for beginners as it's sickly sweet and damn potent).
I would have thought all food would have been expensive in Japan... I believe the Japanese spend much more of their income on food than Americans or Brits... Even rice is more expensive than in the US or UK!
Soba is likely to be just noodles really.. Most of it nowadays is made majorly of wheat flour with minimal amounts of buckwheat ( soba means buckwheat).
In terms of resorting to " cooked food ", well obesity and degenerative disease has risen in Japan over the past decades, but the intake of fruits, vegetables, meat, fish and dairy have all increased. The only thing to decrease has been of staple starches, and the carbohydrate intake has dropped from over 400 grams to around 250g.
If anything, we need to look at the whole picture... Carbohydrates are Human fuel that should make up the majority of the diet. Don't get lost in pointless distinctions when you are in such a confused state.
Simple... Just eat boiled cereals/tubers if you "can't get fruit", and this will prevent you doing nonsense like having maniranara, pestos or whatever.
finish you dinner by 5pm or as early as possible to end your bloat
digestion needs time to rest