Mitsuyo Maeda, Carlos Gracie's original sensei, was a Kodokan Judo instructor who's specialty was ground fighting (newaza). This type of ground-only fighting is often referred to as Kosen Judo. While BJJ did not directly come from Kosen Judo, it is important to understand that Judo has always included all of the ground fighting techniques that are popular today in Brazilian Jiu-Jitsu.
Kosen Judo (高專柔道) refers to a set of competition rules of Kodokan judo with particular emphasis on ground grappling techniques such as pinning holds (osaekomi-waza), joint locks (kansetsu-waza) and chokeholds (shime-waza), referred to as newaza in Japanese martial arts. (Read more here)
Kosen Judo in Montreal is taught by Sensei Hiroshi Nakamura and