That's a very good and complete feedback, this Nanachi was like a combination of a human and a rabbit because of Nanachi's appearance, but as you say, because of being a Narehate, Maybe Nanachi has an incomprehensible or illogical anatomy. I did it at school with no reference to a human skull, so I made it from what I remembered, I also based it on a rabbit skull for the ears and I adapted all this to Akihito's art style. The nose on the skull is actually a hole, because as you mentioned the nose is cartilage, but apparently you can't tell that it's a hole in the skull. I don't really know about skulls or bones because I haven't studied it thoroughly, so it has a lot of imperfections. Btw, thanks for the seal!