Ok, a semi useful post of where to get stuff for any aspiring Japanese players as it can be a wee bit difficult to track down.
Warlord - the best IMHO
The Assault Group - they do nice Flamethrowers/Suicide Teams/SMGs as well, although Warlord have just released theirs.
Brigade Games - they do an Anti Tank Rifle but again Warlord have just released theirs. More like 25mm or even 20mm than 28mm though.
Company B - they do IJA on bicycles.
Black Hat Miniatures: Bamboo Spears - the one 25/28mm Bamboo spears I have been able to find - not sure on quality yet as they haven't arrived.
Company B - do a really comprehensive range including some more esoteric ones like the Ho- Ni Mk1, Te-Ke tankette and Ke-Nu tanks, as well as a Kurogane and Isuzu trucks and some landing craft and AA searchlight vehicles.
Warlord - obviously.
Hobby Armor Depot - do the only Ho-Ro in 1/56 I have seen but the quality doesn't look great and their reputation isn't fantastic. If anyone has bought from them please let me know.
A bit sparse this one - I am using Warlord's Polish 75mm but apparently there is some Japanese artillery on the way from them.
Company B - they do both the 37mm and 47mm anti tank guns, the crews are a little small though - I have used the crew from the Warlord 70mm Mountain Gun, or you could make some up easily enough from the Warlord plastic kit. They also do the 20mm AA gun.
Hope that helps!