Kyusho Jutsu is the method if attacking the vital points on the human body.

Ryukyu Kempo is really split between Oyata's group (the originator of the system) and George Dillman's camp (with offshoots from Dillman).

From this point forward I will discuss Ryukyu Kempo in Oyata's Lineage as this is what I train in:

Oyata's Ryukyu Kempo can be split into 3 section: Tuite Jitsu (joint locks), Kyusho Jitsu (vital point strikes) and Atemi Jitsu (distracting blows which weaken the body). All sections are taught to blend into each other as one single unit.

Kyusho Jitsu was a seemingly "lost" art which was re-introduced primarily by Oyata and Hohan Soken (although there were others out there) through a series of seminars.

In my opinion Oyata's version of Kyusho Jitsu is more realistic when compared to others who use Kyusho Jitsu being the fact that once it is learned you are taught to use it in a more full contact arena (Bogu Kumite). Others that I've seen tend to use a more static approach, which in my opinion, leads to false confidence in the true technique against a moving opponent. Of course I am biased due to the fact that I've been training this system for 12 years.

Side Note: Noticed that I've been quoted based on a previous post LMAO I am honored!
"I'm gonna come at you like a spider monkey"