Board Thread:Game Updates/@comment-1820055-20150930021406/@comment-91.121.132.228-20151014114005

kancolle-db lists Isokaze sightings as 1-5I, 1-6B, 2-5L, 5-3K and 6-3J. Those are all boss nodes aside from 1-6B, which is the south route final node. There's no guarantee that these are the only nodes where she drops, but if there are any others, they're probably places where the possibility of farming is purely theoretical, like "5-5K, only on S-rank."