Engineering student-getting visa with a bump?

I am 26 and doing a mechanical engineering degree at one of the leading UK universities.
I have good grades (going for 1st class Hons) and all that stuff.

However I have an issue from 8 years ago. I had to pay a £100 fine for common/simple assault charge.

Unfortunately this is not France nor Germany nor any other of the vast majority of EU countries where minor offences that occur long time ago get automatically removed from the police database, here they are held indefinitely (at least for now).

Does anyone know of the best way to deal with my situation? I've been told that I can still go to Japan and get a working VISA as they don't require police checks, but if I were to apply for a residence permit they would require it, and I eventually really hope on getting it by contributing to the Japanese society somehow.

What to do (other than consult an immigration lawyer)? Anyone understands the ins and outs of it? I really don't want to feel like all is lost because of something very stupid I have done long time ago which I regret. Anyone giving any advice would be welcomed.

As far as I know, unless you have either (1) drug, prostitution, or human trafficking related criminal record or (2) other crimes for which a prison sentence of a year or longer was given, you should be able to enter Japan.

Note that even when you come as a temporary visitor (tourist), there is a question on the immigration card which asks you whether you've ever been convicted. I cannot suggest to you what you might want to do about that question on that form.

I don't think they do police check when you apply for a work visa (or when your employer-to-be applies for a work visa for you), neither for "permanent resident" resident status (if that is what you mean by "resident permit").

Search the forum for other threads on this topic - they might be somewhat dated, but there have been some threads where people contributed to with their experiences.