Board Thread:General Discussion/@comment-24189673-20131222191208/@comment-1268838-20131222201220

The "monster" on the scroll was Yamamoto himself. Yhwach stated that the original Gotei 13 was little more than a band of ruthless killers. In trying to take revenge on Yhwach, out of sheer anger Yamamoto tried to become that monster again, and died because of it.