Sumi gaeshi video
Info about "Sumi gaeshi video"
Sumi Gaeshi (corner counter) is one of the original 40 throws of Judo as developed by Jigoro Kano. It belongs to the fourth group, Dai Yonkyo, of the traditional throwing list, Gokyo-no-Nagewaza, of Kodokan Judo. It is also part of the current 67 Throws of Kodokan Judo. It is classified as a rear sacrifice technique, Sutemi-waza. 
Sumi Gaeshi is effective when uke leans forward. When attempted, this throw involves a risk of getting caught in a hold. This can happen if uke blocks the attempt after tori is on her back on the mat. Rear throws are usually good counters to this sacrifice throw. 
From Wikipedia  and princetonjudo.org