[Even Setsuna knows it's not that simple. It's so much more complicated, but it's easier to sum it up. He's more than happy for a topic change, and even grins cheerfully when Mitsuhide asks about cardboard.]

[Right!]

They're boxes. They're made out of cardboard. Cardboard is made from trees. We mainly use them to store crap in. Probably takes a lot of trees, though.

[Setsuna opens one and pulls out a soccer ball.]

See? Things.