They're not compatible and shouldn't be a couple regardless even if they were the same age AA hon
Well... about that... sensei always writes incompatible and kinda toxic couples, and we eat it up :P . I mean the minor could be a problem if there isn't a time skip, but besides that such odd coupling isn't unnatural for Nemui. It's almost like a manzai shtick
TH0UGHT AUTHOR MADE A YURI PLEASE PELASE PLEASE