We really need an ass_wings tag

Yeah there should be some distinction between normal wings and these, I've always wondered why they place them there.

Even the Yatagarasu eye is staring at us.

Also, RE:Buttwings
I think it may have been started when someone thought, 'hmm, the pelvis is the most stable part of the skeletal system, let's hook the wings there, instead!'
No proof, though. Just a hunch.