User blog comment:Xilinoc/Ch. 566 (not out yet, but dis gon b gud)/@comment-8669536-20140129172732/@comment-26420452-20140129190828

NaNaNa seemed to watch Renji sleep for more than two hours... He could've easily killed the fool.

As for Rukia, either she's gained something from the Royal Guard training or just like her brother, she's able to resist through sheer willpower.

@TomServo, she must've acquired her Bankai (with or without Ichibei's help); I can't see any Sternritter being defeated without one.