Also, I don't have Turnbull's book right now, but I suspect that you are misinterpreting this passage in your own way. It's been awhile, but I don't recall him stating that support crews aren't combat prone as any army on the march will leave a part of their men guarding the logistics as well as a part of their army making camps, engines, and digging ditches. That however, does not mean these men aren't part of the army. In Li Jing's treatise of the 7th century Tang army for example, described that out of an army of 20,000 on the march, 8,000 are to guard the supply line and he did not describe the exact component of these units either as they weren't part of the regular fighting division, but they had weapons to fight nonetheless. If so, there is no reason to exclude these men from the list of soldiers as not a single source I've came across did this so please cite where Turnbull made the claim that logistic crew are not fighting men.Japan had far fewer harquebusiers than they claimed. During the Imjin invasion, the fourth Japanese division, leadered by Shimizu Yoshihiru, was composed of (Turnbull, Samurai Invasion, pp.44-45):
*3,600 ashigaru, of which
-300 spearmen (of which, 200 pikemen)
-300 flag bearers
4,200 fighting me men, and 5,800 labourers and support crew in general
If we extrapolate this to the entire army, just 42% of men were truelly fighters, which leave the real number of soldiers directly involved in the first invasion at a mere 57,624 men. Of this, a mere 35,71% were arquebusiers, this means 20,577 arquebusiers. The total numbers aren't that different to those of Europe. Actually, the structure of the Japanese divisions, with percentages of fire weapons lower than usual ratios in Europe (50-50 by this time) is oldfashioned, with very weak pike formations and a large number of outdated bows.