Late to the discussion here, but with respect to Sam Hawley's book on the Imjin War, yeah, not so much. It's pretty flawed in lots of ways, partly because it's based on other people's translations of the original sources. And he's writing solely from the Korean perspective. The problem with that is that the war, though fought in Korea, was actually a war between Japan (or more accurately Toyotomi Hideyoshi) and the Ming Empire of China. Korea was just in/on the way. At least Stephen Turnbull, for his flaws, reads Japanese and does some of the original source research itself. But his books are all from the Japanese perspective, though they are more readable than Hawley. The problem with studying that war is that there are just too many sources, written from three perspectives. My own book on the war is explicitly written from the Chinese perspective, though I use Korean & Japanese sources too. The primary Korean sources from this era were written in classical Chinese, as were many of the Japanese sources.
For those of you who might be interested: https://www.amazon.com/Dragons-Head-Serpents-Tail-Commanders/dp/0806155817/ref=sr_1_1?keywords=dragon's+head+and+a+serpent's+tail&qid=1565459720&s=gateway&sr=8-1
That war does have some pretty interesting possibilities for campaign ideas, including lots of courtier intrigues, by the way. And yes, according to some sources the Japanese did use shinobi in Korea.