User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-1359322-20141213111708/@comment-16281343-20141216010413

He also mentioned about the peace treaty w/c isn't that relevant in 18 & 19.

So, basically he mentioned the similarity between 3 & 4 and 18 & 19 w/c both centers on Kiba, Xenovia, and Irina. Then just included all other things that happened in the earlier duo: Gasper and the peace treaty.