The original Yoshin-ryu jujutsu as founded by Akiyama Shirobei Yoshitoki no longer exists and probably died out sometime in the late 19th Century. The only remnant of the system is the Naginata system which is still extant in Hiroshima Prefecture, Japan.
Hontai Yoshin-ryu has nothing to do with Akiyama's Yoshin-ryu. HYR actually stems from the line of systems founded by Takagi Oriemon Shigetoshi and Takagi Umanosuke shigesada (Takagi-ryu, Hontai Takagi Yoshin-ryu, Takagi Yoshin-ryu etc, etc.)
The systems still extant that are related to Akiyama's Yoshin-ryu are Tenjin Shinyo-ryu jujutsu (An amalgamation of Yoshin-ryu and Shin no shindo-ryu) and Shinto Yoshin-ryu jujutsu. Tenjin Shinyo-ryu at present, is only taught in Japan, Australia and the UK.