Most of the classic 0 gauge trains from Japan pre WW2 and just post WW2 come from Seki, Sakai who probably was a successor to Seki and just post WW2 KTM.  Seki and Sakai also " badge engineered" their trains for different countries for example Stronlite for the UK market.  Peter Dunk has a wonderful collection of Japanese 0 gauge trains and a few years back he and his able assistants displayed probably a once in a lifetime working exhibition of these trains at the Train Collectors Society Summer Show.  Here are some pictures of these rare trains.

Peter's sign

Peter's sign

Stronlite coaches and Peter Dunk

Stronlite coaches and Peter Dunk

Sakai large station

Sakai large station

Sakai and Seki locos

Sakai and Seki locos

Sakai steam and electric

Sakai steam and electric

Stronlite LMS loco

Stronlite LMS loco