Kita has decent expert gain considering all you must do is drop your torps and die. Anyway
I like to use a mixed torpedo launcher setup.
I use x4 because my crew is very heavy. Since you said your crew is at level you can
probobly get away with x5 for now. I also like to mix between mod 1 and mod 3 torpedoes
though type 93 m3 with the mod 3s have too short of range to be of much use on a kita.
Another fun setup is to load up on mine launchers. This only works well on island maps.
Try blocking off the spaces between islands.