This is like...pure undiluted autism
I don't know about that. The "Autism" term is used rather excessively here on the web... The senpai has no social skills. but that's not the same as being autistic. It's pure undiluted social retardation, which hits just uncomfortably close enough to home for me to find this fucking hilarious.
which happen to be fit with autism definition..
Not really. Considering that she constantly goes out of her way to be with her little girlfriend, has constantly show herself capable of knowing when someone has stepped out of line and need to be corrected (the cousin), has a sufficient (if hilariously bizarre) understanding of norms and social etiquette, and, on top of everything, is able to pull not only the ojou, but the senpai act (both which are very obviously social constructs) I say she's more likely to have some form of social, not neurodevelopmental, disorder