There has been a resurgence in interest in Kosen Judo in recent years due to its similarities with Brazilian Jiu-Jitsu. Kosen Judo was a refinement of Kodokan Judo that was developed and flourished at the Koto senmon gakko technical colleges in Japan in the first half of the twentieth century.
Kosen Judo's competition rules allowed for greater emphasis of ne-waza (ground techniques) than in mainstream judo and it is regarded as a distinct style of judo. Kosen is an abbreviation of Koto senmon gakko, literally 'Higher Speciality School', Colleges of Technology in Japan that cater for students from age 15 to 20.
The Kosen schools started holding inter-collegiate judo competitions from 1914. Kosen judo rules for matches allow competitors to enter groundwork however they wish and to remain in it as long as they want. The rules allowed for a more tactical style of newaza to develop and the style is popular for young and old alike.