Kani-basamiKodokan Definition, the 1980 Fracture, Research and Current Hansoku-make Rules

01 / What is kani-basami?

What is kani-basami?

In the Kodokan’s classification, kani-basami is a throwing technique (nage-waza) in the side sacrifice group, yoko-sutemi-waza. It is number 15 of the 16 yoko-sutemi-waza. The thrower drops the body sideways and brings the opponent down by holding the opponent’s lower body between both legs.

Kani-basami is still among the Kodokan’s technique names, but under the rules of the International Judo Federation (IJF), applying it is hansoku-make for an act against the spirit of judo, and the athlete cannot take part in any further contests at that event. The same applies in Japan, both at domestic events run under the IJF rules and in contests for junior high school age and younger that are based on the IJF rules (section 6).

A case is on record in which uke broke a shin bone in a contest (section 5). A Japanese research group has suggested that, when uke resists being thrown, a large bending force may act on the shin bones (section 4).

This guide sets out how kani-basami is defined, why it is regarded as dangerous, how it came to be prohibited and which rules deal with it today. Because it is a technique that leads to hansoku-make under contest rules, this guide does not explain how to apply it, how to enter it or how to practise it.

02 / Reference videos

Reference videos

Reference videos to help you picture the movement.

Kodokan official videos

• Kani-basami: a video on the Kodokan’s official YouTube channel. The kani-basami entry in the Kodokan’s list of technique names links to it, and its description says it is part of the Kodokan × IJF Academy “100 Techniques” series.
• Yoko-sutemi-waza: a video on the same channel covering the side sacrifice techniques. The “Yoko-sutemi-waza” heading in the Kodokan’s list of technique names links to it.

03 / Definition and classification

Definition and classification

The Kodokan’s definition

The Kodokan defines kani-basami as follows:

“A technique to throw down the opponent while holding his lower body with both legs by breaking his balance backward, turning the body toward his left side and putting the right leg on his lower abdomen and the left leg on the backside of both of his knees while laying down the body onto the left side.”

This guide gives the definition only as a quotation, so that the technique can be recognised. It does not break the movement down into steps or illustrate it.

Where it sits in the classification

In the Kodokan’s classification, throwing techniques (nage-waza) are divided into standing techniques (tachi-waza) and sacrifice techniques (sutemi-waza), and sacrifice techniques are further divided into rear sacrifice techniques (ma-sutemi-waza) and side sacrifice techniques (yoko-sutemi-waza). Kani-basami is one of the side sacrifice techniques, in which the thrower drops the body sideways.

Relation to the Gokyo

Kani-basami is not in the original Gokyo-no-waza set out in 1895 (42 techniques), nor in the Gokyo-no-waza as revised in 1920 (40 techniques). It is included among the yoko-sutemi-waza in the Kodokan technique names established in 1982 and revised in 1997, and it is listed as a yoko-sutemi-waza in the Kodokan’s current list of technique names (100 techniques).

How it differs from a similar side sacrifice technique

Kawazu-gake, another yoko-sutemi-waza, is a technique in which the thrower entwines one leg around the opponent’s leg from the inside and falls together with the opponent. Its form differs from kani-basami, which holds the opponent between both legs, but in the IJF rules the two appear side by side as techniques that lead to hansoku-make, after which the athlete cannot take part in any further contests.

04 / Why is it regarded as dangerous?

Why is it regarded as dangerous?

The force on the shin bones

In the early 1990s, a research group in Japan set out to measure how dangerous kani-basami is. Their reasoning was that, because kani-basami traps the opponent’s legs between both of the thrower’s legs, if uke resists being thrown, the force of the scissoring legs acts as a bending force on the shin bones (the bones of the lower leg). The researchers wrote at the time that in contests the technique often injured the opponent’s lower leg, and that if safety was the priority it would be desirable to make it a prohibited technique, but that no study had yet examined how dangerous it was.

In the study, strain gauges were attached to two glass-fibre poles standing in for one leg. University judo club members applied kani-basami, and the bending force at the part corresponding to the shin was measured. The values were compared with an approximate threshold at which the tibia, the larger shin bone, breaks.

What the research showed

The authors suggested that, when the technique is fully applied, uke’s knees are held fixed and uke resists being thrown, a bending force large enough to break the tibia may be applied. They also inferred that the fibula, the thinner bone on the outer side of the shin, is quite likely to break as well.

The authors themselves also set out the limits of the study. In real situations there are uncertain factors, such as how the opponent’s legs move, the soft tissue such as muscle, and the combined strength of the tibia together with the fibula, so it is difficult to predict a fracture from a simulation. They did not examine the bending strength of the fibula. The participants were a small number of university judo club members, and the study did not measure fractures in living bone.

Recorded injury

The fracture case of a contestant thrown with kani-basami is described in section 5.

In his 2010 New Year message, Uemura Haruki, then President of the Kodokan, also recalled that kani-basami had been prohibited as a “dangerous technique”.

05 / How it came to be prohibited

How it came to be prohibited

The 1980 injury

In May 1980, the +95 kg category of the All Japan Weight Category Championships, which also served as the final selection event for the Moscow Olympics, was held as a round-robin league of four athletes. At this event, Yamashita Yasuhiro broke his leg when his opponent Endo threw himself into a kani-basami. In an interview, Yamashita himself said, “I broke my left leg” (translated from the Japanese), and that the contest could not be continued and the injury took three months to heal fully. A profile article from the same foundation that published the interview records the broken bone as the fibula of his left leg.

The prohibition in rules and teaching materials

From the documents we were able to check, the treatment of kani-basami can be traced as follows.

• International Judo Federation technique names (established 1995, revised 1998): listed as one of four “prohibited techniques”, together with ashi-garami, do-jime and kawazu-gake.
• Kodokan Judo refereeing rules, junior rules (amended January 12, 2000): in contests for junior high and elementary school pupils, applying kani-basami was hansoku-make. These rules appear as an excerpt in the 2013 teaching guide of Japan’s Ministry of Education, Culture, Sports, Science and Technology; we could not confirm whether the same provision is still in force today.
• The ministry’s teaching guide (2013): given as an example of a prohibited technique not to be used in physical education in the first and second years of junior high school (section 6).
• Current IJF rules (version of July 24, 2026): listed as an act leading to hansoku-make against the spirit of judo (section 6).

06 / Current rules

Current rules

The main provisions that name kani-basami and set out how it is treated are as follows.

Reading the rules

• This IJF provision names kani-basami by its technique name only (the All Japan Judo Federation’s Japanese text likewise says “apply kani-basami”) and gives no description of the movement. The provision contains no wording that makes an exception for any situation.
• Under the IJF rules, before hansoku-make is awarded, the referee consults the IJF Head Referee Director(s) or Referee Supervisor(s).
• The ministry’s entry is part of the “attitude” content that pupils are to acquire in physical education at school, and it appears in the column for the first and second years of junior high school. The columns for the third year and for senior high school do not name kani-basami. It is not a provision that bans practice in dojos or school clubs in general.