No idea wheat the OP’s budget is (including petrol to go looking for cars).
Costs to import a car to order is not the same as the retail price of such cars on the forecourt. Dealers add a margin of upto 100%. Their money is tied up at sea for 6 weeks. Its a different proposition when its someone else’s money, and they are performing an essentially risk free service; their guarantee is usually along the lines that the cars selected will be something they would be happy to sell themselves here.
Looking at retail price cares (cars at auction will be cheaper):
https://www.carsensor.net/usedcar/detail/VU1693406689/index.html?TRCD=200002
Nice 79k km RS model, 528,000 Yen, or £4000.
Add £500 Agent/FOB fees, £500 shipping, 10% duty, 20% duty, £200 UK dock fees, £500 importer fee =£7300, plus allow £500 for UK service MOT (Yokohama tyres on that, so wouldn’t anticiplate any issues). Auction car would be half the price? This car appears essentially as new, and is the desireable RS model (more power).
https://www.carsensor.net/usedcar/detail/CU3423812685/index.html?TRCD=200002
V-Spec NB1, with 81k kms. Being a NB1, it will have the proper Torsen diff. 408,000 Yen. £3100 to purchase, £6100
The cheapest 1.8 manual retail:
https://www.carsensor.net/usedcar/detail/CU9225020604/index.html?TRCD=200002
227k kms, 250,000 yen, £1900
Prices are cheaper is you include the 1.6 model
https://www.carsensor.net/usedcar/detail/VU2216095259/index.html?TRCD=200002
150k kms, 128,000 yen, under £1000. Looks to be in sweet condition.
And these are retail dealer prices (there isn’t really a private used car market in Japan), not auction.
You can go via a Japan exporter, from stock, where they are buying cars at auction, adding a markup, and then you deal with the taxes and fetching the car home at the other end
https://www.beforward.jp
You can bid on cars yourself, though that I suspect can be fairly nervewracking. And most of these Japan-based exporters are fronted by Australians. New Zealanders. You can sign up to various websites, and see the auction prices (sold prices), but you can short cut that effort with Autolinkuk.