In~su~la~ted sleeping bag. It does the job pretty well.

[ And is much better than sleeping under a hoodie in a tree. Now he can sleep in a sleeping bag in a tree. Much better. ]

Other than that, some extra clothes. So I'm not just wearing these ones all the time. [ Might not be a bad idea to follow his lead there, Akechi. When did you last wash those clothes...? ]