From the world of Final Fatasy X, It is the secret Aeon Yojimbo's overdrive. Unlike all the other Aeons. Yojimbo need not use Zanmato when his overdrive guage is full, but uses it at random when your relationship with him is high enough, (zanmato level 10 is required to kill Penance with this move)or when he is payed enough. (hoewver paying him alot of Gil does not guarantee the move)
That Zanmato move of Yojimbo's kills ANYTHING in one hit!! AMAZING!!