Ok so ive heard alot about how its a lost jutsu but i do not believe that. So the only thing that could of happened is either it was written down in a scroll or someone secretly learned it.
Kakashi probably learned it he was in the leaf when the nine tails attacked and do they not call him the copy cat ninja so i bet he knows it and hes gonna use it
either that or orochimaru learned it since it did seal his arms away so id say if my arms got sealed away to where i couldnt use jutsu and that was my liffe goal id probably learn the move that took them away and remember that shit just saying