UK visit visa denied for lack of financial proof. Should I reapply, claiming my uncle as a sponsor?

You really need bank statements going back at least six months and covering the entire period from start to finish. A year’s worth of statements would be better. What they’re interested in seeing is not the balance on any given date, but the pattern of balances on your bank account over a period of time.

Interesting problem. I took my Japanese wife to London for sightseeing during our stay in the Netherlands without any prior arrangements (since she has already cleared the EU border at that point and Brexit didn’t exist). They gave us some stern looks and tried really hard to pretend we still have borders inside of the EU (ridiculous, we don’t), but let us in without checking anything.

Once you are inside of Europe, you should be able to travel freely within the EU. Especially with a Japanese passport, which are well regarded globally.
In case you are not Japanese, a rental contract doesn’t mean much, you should supplement it with your work visa as evidence.

Regarding the financials, they just want to know you have enough money available during your stay to support yourself. they can’t see the transactions going in and out of your back account. If you show up at the border with 1700GBP you can’t tell me that this is not sufficient evidence that you have this money directly available to sustain yourself. That or show them your contract at your employer, clearly showing your income and its duration, with bank statements as backup.

One potential red flag for them might be flying to Ukraine, I myself would wonder what business you have there, since eastern Europe doesn’t quite have the best reputation among western countries.

The rules regarding tourist entry into countries are largely the same across the world, and if you can provide evidence that shows you can support yourself, your accommodation(s) and plans once in the UK, you should be good to go.

I believe technically it’s not even a visa, there are just some rules for entry to the country under visa exemption and they need to know you will leave and won’t burden the country.

… It just dawned on me that if you have a EU passport there should be no trouble going tot he UK to begin with, since you have the right to free travel within the EU zone (until they leave, of course).

It seems to me that just showing up at the border (with supporting evidence) should work (I understand that this is scary), but that depends on which passport you carry. My wife used to work at a travel agency and recommended this approach to me when I came to japan the first time, and I’ve been flying this way for the past 5 years.

The UK immigration service will refuse you on absolutely anything they can, so I suggest including the following information in addition to what you already provided:

• The bank statements you plan to include, ideally going back several months. You may be able to get them by visiting the bank in person. If they offer to print them out have them stamped as authentic.

• A copy of the refusal letter and a cover letter saying that you understand the decision and have included additional information to address the issues raised.

Don’t change your story, stick with your original plan. If you try to say that someone else will cover your costs they will just use it against you, claiming that it isn’t clear what you are planning to do.

If possible take some legal advice by getting your application checked first. I know it’s very expensive but it’s worth it. Your boyfriend in the UK best placed to do this, as you really need a UK lawyer who is familiar with the system.

I’m afraid it is very difficult to get a UK visa at the best of times.

Your uncle is irrelevant. If you claim to have a bank account but persist in withholding the statements, whatever the reason, the ECO will conclude that you’re hiding something and refuse your application.

You already have one refusal. A second refusal will make life very much harder. Do what you have to do, but get the statements.

You need your bank statements.

Since you are decently employed with an ongoing work visa for Japan, suddenly switching to saying your uncle will pay for everything and still not showing your own financial circumstances makes your application much weaker as well as inconsistent with the previous application and I can only presume it will be rejected.