refers to a set of competition rules of Kodokan

Kodokan

, or the Kodokan Institute, is the headquarters of the worldwide judo community. Literally, kō means "to lecture" or "to spread information," dō means "the way," and kan is "a public building or hall," together translating roughly as "a place for the study or promotion of the way." The Kodokan was...

 judo

Judo

is a modern martial art and combat sport created in Japan in 1882 by Jigoro Kano. Its most prominent feature is its competitive element, where the object is to either throw or takedown one's opponent to the ground, immobilize or otherwise subdue one's opponent with a grappling maneuver, or force an...

 with particular emphasis on ground grappling

Grappling

Grappling refers to techniques, maneuvers, and counters applied to an opponent in order to gain a physical advantage, such as improving relative position, escaping, submitting, or injury to the opponent. Grappling is a general term that covers techniques used in many disciplines, styles and martial...

 techniques such as pinning holds (osaekomi-waza), joint lock

Joint lock

A Joint lock is a grappling technique involving manipulation of an opponent's joints in such a way that the joints reach their maximal degree of motion....

s (kansetsu-waza) and chokehold

Chokehold

A chokehold or choke is a general term for grappling hold that critically reduces or prevents either air or blood from passing through the neck of an opponent. The restriction may be of one or both and depends on the hold used and the reaction of the victim...

s (shime-waza), referred to as newaza in Japanese martial arts

Japanese martial arts

Japanese martial arts refers to the enormous variety of martial arts native to Japan. At least three Japanese terms are often used interchangeably with the English phrase "Japanese martial arts": , literally meaning "martial way", , which has no perfect translation but means something like science,...

.

Background

schools started holding their own judo competitions from 1914. The rules of a Kosen judo match were mainly Dai Nippon Butokukai and Kodokan rules prior to 1925 changes. They allowed direct transition to newaza, enabling scenarios where one less skilled judoka could drag down the other into newaza (a tactic modernly known as pulling-guard), and this was exploited by some teams that matched their less skilled students against the more skilled students of the rival teams, aiming at a draw in newaza. To achieve victory under the judo rules of the time the judoka had to score ippon

Ippon

Ippon literally "one full point", it is the highest score a fighter can achieve in a Japanese martial arts ippon-wazari contest, usually judo, karate or jujutsu.-Ippon in judo:...

 as there were no intermediate scores, or a draw was declared at the referee's discretion.

1925 changes were largely a reaction to Kosen competition's emphasis on newaza. As opposed to earlier ruleset, transition to groundwork was limited by much stricter rules and by 1929, yusei-gachi rule was introduced to end draws in matches. However, Kosen schools continued to hold tournaments with former rules.

Kosen judo style

Kosen judo, as a distinct style, flourished in the Kyoto

Kyoto

is a city in the central part of the island of Honshū, Japan. It has a population close to 1.5 million. Formerly the imperial capital of Japan, it is now the capital of Kyoto Prefecture, as well as a major part of the Osaka-Kobe-Kyoto metropolitan area.-History:...

 region until around 1940. The style and the peculiar ruleset is still studied for tournaments of (former) imperial universities and is taught especially in Kyoto.