Seoi Otoshi (背負落) is one of the preserved throwing techniques, Habukareta Waza, of Judo.

[2] Seoi otoshi begins with one judo player (tori) breaking another's (uke's) balance in the forward, or right front corner direction.

Similar to Tai Otoshi, Ukes movements can be limited or blocked by Toris leg.

In Tai Otoshi the leg off Tori can be extended to push uke over.

Extension of the leg in Sei Otoshi will rather lead to a lifting effect due to the fixation point of the working hand.