Sumi-gaeshi in judo: what this sacrifice throw is, why it is in the DJB syllabus, and how to build it safely through breakfalls and a coach.
The honest answer: sumi-gaeshi is a sacrifice throw in which you let yourself fall backwards onto your back and tip the opponent over the "corner". It is not a beginner's throw. In the German Judo Federation it belongs to the extension programme and is mandatory for the 2nd kyu (blue) exam because it teaches you to throw from an unusual grip as well [1].
The family is called sutemi-waza, "sacrifice techniques": you land on your back or side yourself in order to throw the opponent [2]. Sumi-gaeshi is a ma-sutemi, so a throw backwards, and belongs to the fourth group of the Gokyo [3]. It is described like this: you grip uke's judogi, place a foot or knee against his opposite thigh ("careful, not into the groin") and roll backwards so his own momentum carries him over you [3].
Why the caution in this guide? Because with throwing injuries, falling counts. At international tournaments 25.85% of standing injuries happened directly during the throw and 14.77% during falls [4]. A review names "being thrown" as the most common injury mechanism; serious injuries are rare and mostly affect brain and spine [5]. Sacrifice throws are named that way for a reason: you are part of the fall.
How long does it take? Count in months, not weeks, until the entry works without hesitation. That is experience, not a study.
This guide describes the learning stages, not the technique on a partner. Your coach shows you the execution.
On a mat, from a squat, you practise rolling backwards onto your back: chin on chest, back rounded, arms not flailing backwards but placed under control. Breakfalls reduce the impact load; in a review, clean breakfall technique stayed below the injury threshold, whereas direct occipital contact did not [6]. Milestone: 10 calm backward rolls in which the back of your head never touches the mat.
You repeat the line of movement tomoe-nage and sumi-gaeshi share, first solo or with a light grip only. Milestone: your coach says you keep control of your neck when falling back.
On the coach's instruction: take the grip and indicate the entry without falling. You practise breaking your partner's balance (kuzushi), not falling. Milestone: you recognise when uke is on his forefoot without rushing.
Only now, on the mat, with the coach right beside you and a very secure uke, does the fall become a throw. The coach decides direction, tempo and number of attempts. Milestone: you land before you let go of the opponent, and uke lands under control.
Only after clearance from your coach and only with partners who know the rules. In competition the IJF assesses uke's landing on the back and controlled execution [7]; actions that count as "diving" are punished by the rules with hansoku-make [8]. Your coach shows you exactly what falls under that.
This guide explains and motivates; it does not replace supervised training or a coach.
Have your coach film your training from the side. Do not watch the throw, watch your head. If the chin stays down, the throw stays controllable. You do not learn such small details from the mirror. That is experience, not a study.
No. The German Judo Federation lists it in the extension programme and requires it only for the 2nd kyu [1]. You learn it after basic throws, secure breakfalls and tomoe-nage.
Sutemi-waza are throwing techniques in which you yourself fall onto your back or side to throw the opponent [2]. Ma-sutemi-waza throw backwards, yoko-sutemi-waza to the side.
Like any throw it can cause injuries, particularly to neck and shoulders [5]. With breakfalls, a mat and supervision you lower the risk; you can never remove it.
Only the backward roll on a mat. You practise the throw on a partner exclusively in training under supervision.
Yes, in judo it is a recognised throw. Which actions are penalised as diving and how ippon is awarded is regulated by the IJF rules [7][8]; your coach explains the exact interpretation.
Learning Nage-no-kata: the Forms of Throwing in Judo – Structure and Learning Path