There is a rather delightful story associated with this ryu. About 40 years ago, my instructor was in an antique shop in Kamakura, and found a makimono for Fujiwara-ryu. Upon unrolling it, he found to his surprise that it was identical to the Isezaki Araki-ryu, with the exception that the first generation in the lineage chart was an otherwise unknown Fujiwara Kamatari. From the 2nd generation, the lineage descended through Mori Kasuminosuke to Kikuchi Kenko Noriyuki (菊地拳光則) in beginning of Meiji period. (Note that the character "Ken" in Kikuchi's name is "fist," the same character in the word, kenpo, the appellation that Isezaki Araki-ryu attached to their group in the Meiji period).
He brought this makimono back to his teachers in Isezaki, to be greeted with astonishment from Kikuchi Genkichi. "That's Uncle Kenko! He's a family legend. One night he just left town and was never seen again. So that's what happened to him!'
Apparently Kenko, a 14th generation shihan of Araki-ryu, set up a school of his own in another area, covering his tracks by changing the ryu name.