I think the tree analogy is probably connected to, or in reference to Koji Kashin specifically. I can understand the concerns about what his genjutsu could do in the modern interconnected world. I think UN's whole point of existing may be to fight or stop Koji Kashin directly. Their issue with NIN isn't really about their mere existence or different ninja factions. Could it be more about the fact that NIN is a tool of Koji Kashin. And he has absolute control of NIN via his genjutsu. Despite being ninja it seems very, very few from NIN are even aware of the genjutsu. Being capable of resisting it and/or breaking the spell is another thing all together. Sounds like it's time for my boy Kato to get back to work. I think his place in the showdown is starting to come together. Also curious about who Hachia is cruising around with? Are they looking trouble or allies? Who was on the other side of the phone call with Juro? What is Ranran wanting out of all of this? And where do her loyalties ultimately lay? Where and how does Sasama fit into all of this? I don't think she is 100% NIN and hasn't been for a while.So the tree is an analogy for ninja infiltrating society and steering it towards conflict in order to justify their ow existence
Wonder what is the thing that is within the weird tree, which is in itself inside a shrine, which is in itself underground
The flower that blooms at the bottom of the shaft
Tbh that's the sort of analogy that's right at home in a series like thisMaybe it's the butthole