...there a tag for when something is walking up a wall? i feel like there should be one if there isn't.

So it's not only Osa-Orin that can walk up walls... I guess we can mark this as a "Universal Trait"

Well, that's slightly terrifying.

If these things ever turn against us all hope is lost, but until then they are the best thing to happen

I've just realized... Osa-Akyuu doesn't try to make itself into a pillow for Akyuu.

Pretty much every other one we've seen in a similar situation has done so, causing nightmares or otherwise strange dreams (intentionally or not), but this one just supplies a blanket before leaving. It may be due to that Akyuu tends to fall asleep while working, but it is still a significant deviation from normal Osa- behavior.

Dakkan said:
I've just realized... Osa-Akyuu doesn't try to make itself into a pillow for Akyuu.

Pretty much every other one we've seen in a similar situation has done so, causing nightmares or otherwise strange dreams (intentionally or not), but this one just supplies a blanket before leaving. It may be due to that Akyuu tends to fall asleep while working, but it is still a significant deviation from normal Osa- behavior.

This means that they're evolving towards their final goal.

And when that goal is achieved, Gensokyo will burn.

Also Osa-Akyuu's still wearing the rope used way back then. Perhaps Akyuu explained its to help mark her as being that individual as she doesn't know that there might be more than one an Osa type

Krugger said:

If these things ever turn against us all hope is lost, but until then they are the best thing to happen

So... kind of like robots, then.