That anatomy dummy running like Forrest Gump around the school and through the streets was hilarious. The disassembly/reassembly trick to evade Momo was pretty genius as well...he just missed a spot. I am really curious now how this thing ended up with Okarun's ball. Also, how these two things ended up imbued with spirits in the first place.
As for Jiji, I can't say I have fully warmed up to him yet. He is so over the top that it feels like a performance. I suspect that we will get more into his story next episode and make him more likeable. It's what they did for Aira, so I think it's what is coming for Jiji.