Board Thread:Questions and Answers/@comment-10797017-20130622101437/@comment-11051098-20130708144713

If it is a Shiba technique, I'm surprised no one have recognized it before. Ichigo have been a Substitute Shinigami for close to 2 years, and always used that technique in his fights at least after achieving Bankai. But we only know of Isshin, other than Ichigo, who has used GT before, so maybe it wasn't known to others at all.