User blog comment:Rejuvenation/Anime episode 250/@comment-1332195-20091215141654

Is it me, or does Muramasa have 2 releases in this episode; both times he releases, the preceding words are different.

Yes, he is called 'Kuchiki Koga' in this. Black spirits? Maybe that's the default for those basement level Shinigami who don't know Shikai or are even close to knowing. Why he stabbed him at the end is a bit of a puzzler. Maybe it to restore the broken zan he's carrying, and it'll be full length next episode.