driver licence

I'm planning to move to Japan in the near future. Recently I have been looking into driving while in Japan. If I have a full drivers licence and obtain it 3 months or more before arriving in Japan I can get a Japanese drivers licence straight away. Which will work out fine for me but I was curious how would a person get a Japanese drivers licence if they full short of the 3 months minimum?

Then you have to start from scratch, as a Japanese person would.

Depends where you are from. Some countries, such as the UK, you can translate your licence right over. Others, such as the US, you need to start from fresh.

If you don't have enough driving experience, you have to start from fresh, irrespective of where you are from.

Driving in Japan isn't too hard, but there are a lot of rules and expenses. If you are based in a medium to large city, there is probably little need to drive.

If you're in the situation where you have your current license for less than 3 months, for example you renew it within three months of your arrival date, you can request documents from your home country proving you've been driving for longer.
If you are new to driving completely, you would have to start from scratch in Japan.

If you're staying for less than a year in Japan an international drivers license might be a better option.

Depends where you are from. Some countries, such as the UK, you can translate your licence right over. Others, such as the US, you need to start from fresh.

That's not quite right. Those that can't convert their licenses directly (US drivers for example) don't need to start from scratch. The process is somewhat abbreviated for them as they don't need to attend classes, but they do need to pass a practical exam. The exam usually takes several attempts to pass.

If you don't have enough driving experience, you have to start from fresh, irrespective of where you are from.

Yes, that is correct. Also keep in mind, starting from scratch typically means a month of Japanese language driving school at a cost of around 300,000 yen, give or take.