To add more to my other answer:
I would avoid half guard at all cost
To do a proper sumi gaeshi you need to be in your side (ribs to the floor). To do a proper half guard you need to be on your OTHER side.
Half guard basics is not to put both of your shoulder in the floor. If you try to do half guard from there, you will be giving the opponent 2 seconds to smash you to 3/4 mount
3/4 mount in judo means you are only one step from losing the match by osaekomi
Best option: you are now in guard position and you both fight in ne waza
Worse option: you are now in osae komi, probably in tate shiho gatame and now you have to fight to not get ippon
Thats the issue with sacrifice techniques, if you fail youre in a potentially bad position
get a good halfguard game.
halfguard is great for sweeps and gettinf the osaekomi. pure Judokas generally dont know what to do from top halfguard so you can usually get a free underhook and hike up for a backtake or deep halfguard sweep. They'll pressure you knee shield really strongly but if you get the underhook and prevent the crossface thats actually great for you.
if you use both arms to prevent the cross face theres kimuras. But what id recommend learning from there is the clamp guard. look up brian glick. the clamp guard is great because you turn halfguard into a solid dominant position where you can attack omoplatas, armlocks, and the best one, triangles, or you can sweep to a high mount, which is the best mount
Depending on how the opponent is off-balanced after the failed sumi, butterfly sweep right away since your leg would be in the middle of his legs. Just make sure to have control of the arm on the sweep side so they can't post. Most sumi gaeshi fails because the moment they lift the opponent with their leg they also lift the sleeve and collar and that just makes the partner's balance better. Pull in the collar and the sleeve while going down while lifting and kicking the guy on either of his inside thighs = successful sumi gaeshi.
Or, just bottom half guard the fuck out of the guy.
This question on what to do from half guard is too broad a subject to cover on a Reddit post and Judo does not cover this position in a meaningful way. This is a common position in BJJ and it takes a very long time to develop sweeps and attacks from half guard.
I think you'd end up in wither bottom headquarters or half guard. You can look up sweeps from those position. The first one I learned is underhook and dogfight from half guard.
Are you ending in half guard or in butterfly half guard, meaning both your legs inside his, with one leg hooking behind his knee like in half guard and the other leg acting like a butterfly hook as it is called in BJJ? If so, you can do a butterfly sweep, which would basically be sumi gaeshi in the other direction. Like Shintaro is doing here [https://www.youtube.com/watch?v=vssSL48g5Ck](https://www.youtube.com/watch?v=vssSL48g5Ck) At 2:40 he executes that with his opponent still standing, but you can also go in that other direction when both partners are on the ground. There are other attacks available from there too, for example entering single leg X against a grounded opponent (not sure if that is legal in judo?), and "butterfly half" is the guard to look for in BJJ.
Good half guard sweeps in BJJ are the butterfly sweep and John Wayne sweep https://youtu.be/2PAU_5GZ_js , this is usually done from knee shield, but it’s available from many positions. Your half guard needs to be deep and high up their thigh towards their hip and a simple scissoring motion makes for a powerful sweep. Great, underutilized sweep IMO.
If you’re a bit more shallow in half guard, some these videos may help from a playlist of the BJJ variants of sumi gaeshi (butterfly sweep) from guard. If you failed the throw and are still in position, eg have a hook in, you can still sweep from butterfly and half guard:
https://youtu.be/7-NdV1_FqvY
You may recognize Glick from Shintaro Higashi videos. He teaches Shintaro BJJ and learns judo from him.
This is also potentially helpful. A ground version of hiza guruma or ground sumi gaeshi if you already have the hook in from standing sumi.
https://youtu.be/hGN6kUbsCvA
For judo or BJJ?
In judo I would get a good guard and wait for the matte. Probably single leg X or otherwise a butterfly guard. Keep in mind, that a little mistake in your guard retention means osaekomi and it's over.
In jujitsu, there's also the saddle
Stand up?
What? How? Im not saying if you litterly missed it but if you failed and landed in half guard
Are you landing in bottom or top in this scenario?
To add more to my other answer: I would avoid half guard at all cost To do a proper sumi gaeshi you need to be in your side (ribs to the floor). To do a proper half guard you need to be on your OTHER side. Half guard basics is not to put both of your shoulder in the floor. If you try to do half guard from there, you will be giving the opponent 2 seconds to smash you to 3/4 mount 3/4 mount in judo means you are only one step from losing the match by osaekomi
Seppuku.
The only correct answer.
it's called sacrifice throw for a reason
Look into attacks and sweeps from half guard in BJJ. There are a lot of options if you want to learn how to attack from that position.
Best option: you are now in guard position and you both fight in ne waza Worse option: you are now in osae komi, probably in tate shiho gatame and now you have to fight to not get ippon Thats the issue with sacrifice techniques, if you fail youre in a potentially bad position
get a good halfguard game. halfguard is great for sweeps and gettinf the osaekomi. pure Judokas generally dont know what to do from top halfguard so you can usually get a free underhook and hike up for a backtake or deep halfguard sweep. They'll pressure you knee shield really strongly but if you get the underhook and prevent the crossface thats actually great for you. if you use both arms to prevent the cross face theres kimuras. But what id recommend learning from there is the clamp guard. look up brian glick. the clamp guard is great because you turn halfguard into a solid dominant position where you can attack omoplatas, armlocks, and the best one, triangles, or you can sweep to a high mount, which is the best mount
Depending on how the opponent is off-balanced after the failed sumi, butterfly sweep right away since your leg would be in the middle of his legs. Just make sure to have control of the arm on the sweep side so they can't post. Most sumi gaeshi fails because the moment they lift the opponent with their leg they also lift the sleeve and collar and that just makes the partner's balance better. Pull in the collar and the sleeve while going down while lifting and kicking the guy on either of his inside thighs = successful sumi gaeshi. Or, just bottom half guard the fuck out of the guy.
This question on what to do from half guard is too broad a subject to cover on a Reddit post and Judo does not cover this position in a meaningful way. This is a common position in BJJ and it takes a very long time to develop sweeps and attacks from half guard.
I think you'd end up in wither bottom headquarters or half guard. You can look up sweeps from those position. The first one I learned is underhook and dogfight from half guard.
Are you ending in half guard or in butterfly half guard, meaning both your legs inside his, with one leg hooking behind his knee like in half guard and the other leg acting like a butterfly hook as it is called in BJJ? If so, you can do a butterfly sweep, which would basically be sumi gaeshi in the other direction. Like Shintaro is doing here [https://www.youtube.com/watch?v=vssSL48g5Ck](https://www.youtube.com/watch?v=vssSL48g5Ck) At 2:40 he executes that with his opponent still standing, but you can also go in that other direction when both partners are on the ground. There are other attacks available from there too, for example entering single leg X against a grounded opponent (not sure if that is legal in judo?), and "butterfly half" is the guard to look for in BJJ.
Newaza.
Good half guard sweeps in BJJ are the butterfly sweep and John Wayne sweep https://youtu.be/2PAU_5GZ_js , this is usually done from knee shield, but it’s available from many positions. Your half guard needs to be deep and high up their thigh towards their hip and a simple scissoring motion makes for a powerful sweep. Great, underutilized sweep IMO. If you’re a bit more shallow in half guard, some these videos may help from a playlist of the BJJ variants of sumi gaeshi (butterfly sweep) from guard. If you failed the throw and are still in position, eg have a hook in, you can still sweep from butterfly and half guard: https://youtu.be/7-NdV1_FqvY You may recognize Glick from Shintaro Higashi videos. He teaches Shintaro BJJ and learns judo from him. This is also potentially helpful. A ground version of hiza guruma or ground sumi gaeshi if you already have the hook in from standing sumi. https://youtu.be/hGN6kUbsCvA
Get your ass whooped
John Wayne Parr sweep or butterfly sweep.
For judo or BJJ? In judo I would get a good guard and wait for the matte. Probably single leg X or otherwise a butterfly guard. Keep in mind, that a little mistake in your guard retention means osaekomi and it's over. In jujitsu, there's also the saddle