I've been playing around with the Katori on custom missions. It's a fun ship to watch from a distance. You'd be surprised how quickly merchant ships blow up when it starts shooting. It's also manned by the most determined crew I have ever seen.
(you can't see it here, but it was still blasting away
)
Just a small niggle: I love the fact that you put it's historical AA upgrade of single 25mm guns, and in it's correct locations. But they're set to appear at the beginning of the war, even thought they should appear by mid '44. Same goes for the 2 127mm flak guns. Could you change it so that they appear in the late war? I can help you with dates and what was added each time, if you need to.