That would be lots of fun:
For smaller figures there are some really excellent historical warrior
figures. Good for a battle diorama. The Western dollhouse people do a
lot in 1/12th scale, A adult human is roughly 4 and a half to 6 inches
tall in this scale. I'm unfamilar with the Japanese doll world, so it's
possible there might be lots available as accessories, not that you need
a lot since most period houses don't have a large quantity of furnishings.
Model railroading supplies are widely available for foliage and for
structures. You may have to get creative with printers for screens,
especially the gold ones!!!
I'm fairly good with miniatures and model railroad stuff. Feel free to
ask questions. For the clothing, costumes, etc. the list certainly has
the requisite 'threadheads'.