It's grimmjow! Don't denie it!
Hint one, the huge slice... brutal .. Hint Two, who else would have scared Urahara by getting close with a SWORD.
"Don't sit there scared like a little bitch, get up and get him out of that .. whatchhya call it..."
What I want to know is how they are controling big guy and the other kid. Aizen on their side?