"The world itself? Did someone do something, or did it just start happening?" Shikamaru may not have the answers, given the lack of information shared, but Chouji asks anyway.

As for the second part, he nods, knowing that Shikamaru is probably figuring out which pieces of information are the most important. "Mm." Chouji will just take note of everything mentioned. 'This enclosure' means there are others, but that can wait.