Mmmh.
People keep calling him a pervert...
Here's the definition from lexico:
a person whose sexual behaviour is regarded as abnormal and unacceptable.
From the Cambridge dictionary:
a person whose sexual behaviour is considered strange and unpleasant by most people
And from merriam-webster:
one given to some form of sexual perversion --> Perversion: an aberrant sexual practice or interest especially when habitual
I really don't see anything sexual in his behaviour.
I mean, the guy's a creep for sure, and his hobbies are strange and out-there, but it isn't sexually motivated, from what I could see.
Ryugasaki-san, on the other hand... now here's a pervert.
She's clearly in want of a sexual experience with him... and they aren't of the same species.
I think that makes her a sexual deviant, and a pervert.