Board Thread:General Discussion/@comment-24189673-20131222191208/@comment-11051098-20131222210639

Yhwach stated that the Yamamoto who founded the Gotei 13, was a ruthless man who sacrificed his own subordinates in battle if he could gain advantages by that.

The monster on the scroll was Yamamoto himself, yes. If you look closely, you can see the back of his head with the hair tuft sticking up, standing in a field of flames.