Board Thread:Naruto Discussions/@comment-24847491-20140921145042/@comment-25442883-20140925150001

I personaly think he did learn from Shikkotsu Forest. Shikkotsu Forest is not called legendary for nothing, together with Mount Myōboku and Ryūchi Cave. I'm not saying it's impossible that he learned it himself, but chances for that is definitley smaller than learning it in Shikkotsu Forest.

Some says why he didn't recognize Katsuyu on battlefield. I have 2 explanation: 1. He didn't have time to pay attention at all since he had focused on stoping Juubi from time he came to battlefield. 2. There are not only Katsuyu's in Shikkotsu Forest, and he learned it long time ago, so there had to be another slug queen or something, so seeing Katsuyu means nothing.