I'm a BJJ praticioner trying to improve my takedowns. I was wondering: is the Obi Tori Gaeshi just a variation of the Sumi Gaeshi or a different takedown? The two takedowns are quite similar, with little differences.
I searched them on Google, but I've found images that look like Obi Tori Gaeshi named as Sumi Gaeshi. I'm confused! Could someone give me some enlightenment?
I take Toshiro Daigo's book Kodokan Judo Throwing Techniques to be the official word on throw classification. Daigo is the chief instructor at the Kodokan, the mother school of judo in Tokyo, Japan.
The top player in the lightweight class was a man named Stepanov, who inflicted pain on many Japanese judoka, with ashi-tori-waza from Sambo Judo, and unorthodox techniques such as obi-tori-gaeshi.
The technique, in which he gripped the back of the opponent's belt and dropped down the rear, has long been called obi-tori-gaeshi, but is in fact the hikkikomi-gaeshi described in sono ni.
"Sono ni" is the second variation/point of the section on hikkikomi-gaeshi, where an over the back grip is taken on the belt.
I think the quotation means that all obi-tori-gaeshi variations are hikkikomi-gaeshi, but it's not totally clear. Hikkikomi-gaeshi is one of the 67 Kodokan-recognized throws, and obi-tori-gaeshi is not.
Obi-tori-gaeshi is on the list of now 68 Kodokan-recognized throws as a te-waza. See john's answer for description and video.
Daigo explicitly enumerates points that differentiate variations of hikkikomi-gaeshi and sumi-gaeshi, so you are in good company regarding the confusion between the techniques.
Without over the back grip:
The key point in telling these techniques apart lies not in the part of uke's leg that tori springs upwards, but in whether he executes the technique from a defensive grappling posture (sumi-gaeshi), or executes it while holding one of uke's arms (hikkikomi gaeshi).
With over the back grip:
The key point for telling these techniques apart lies in whether tori grips uke's back (sumi-gaeshi) or whether he grips the back of uke's belt (hikkikomi gaeshi).
Judo throw classification is a messy business. Throws may have different names at different times, and the points of classification can be quite arcane and perhaps not useful. The difference between sumi-gaeshi and obi-tori-gaeshi is not something I actually remember, but I know where to look it up. I would not expect most instructors to know or care about this difference.
Obi-tori-gaeshi IS pat of the go-kyo. It is te-waza (hand technique). You grasp uke's belt and leg and rotate towards the belt-hand side (clockwise if you're right-handed) while lifting uke's leg.
Hikkomi-gaeshi is ma-sutemi waza. There are two variants: one where you roll backwards and one where you twist underneath.
Watch this if you don't believe me: https://youtu.be/VhH3rXs6cdE
Late answer:
If you want to improve this kind of throws, have a look at the book Fighting Judo by Katsuhiko Kashiwazaki (no longer printed and it's a second-hand collector book now but you can find it online). I am sure you will love it as a BJJer.
Kashiwazaki is a lightweight judoka, 1981 judo world champion & 1975 sambo world champion(!) and technical beast on the ground. So his repertoire is pretty about throws with easy transition into ground techniques.
"Russian" judo is (was because of rules changes) a lot about wrestling moves and sacrifice throws and its no coincidence if sambo is very much alike (after all, it's another sport that is 80% old judo and a some Russian judo champions are samboists wearing a judogi ;) ). So have a look at sambo too!
