My theory is that she, the human girl, must be Iruma's real mother and his parents that "raised" him actually just picked him up or a relative who just used Iruma for bothersome things. Delkira might also have connections to this human girl just like Iruma. And Ameri's mother may also have an interest on humans and don't want to see them being treated like food or alien so she helped this human girl escape with or without Henri's help.
OKAY I SEE YOU
I just can't believe that the extreme sex addict in the club is the first one to retire out of all of them!!