Where on the Museum site am i looking for VSF its all over the place
All i can see at 28mm size is the Samurai.
They don't specifically do VSF, in 28mm they only do samurai, but they are unarmoured and some look ok for VSF character types, perhaps as vehicle crews, commanders, or auxiliaries for the Redoubt Miniature figures.
Alasdair uses some for Urban War SF (as a cut price alternative for Triad retainers).
The rice parcels that the ashigaru wear as a bandolier can be painted up as ammunition (or grenade) pouches. The ashigaru spears can be easily adapted as rockets or assault charges (think dynamite on the end of a stick - bit of a one-shot suicidal weapon, but you did say Japanese VSF)