Synecdoche: 2 books

Massage therapist Naoe gets an unusual visitor to the Smiley Boar clinic: Elfuda, a beautiful elf from another world who’s addicted to junk food! As Naoe works with Elfuda to help her lose her excess weight so she can return home, he starts to realize that there are other fantastical creatures with epic curves in desperate need of his help.

Naoe has been helping Elfuda shed the pounds she's picked up since coming to the human world...but now he's started to gain weight, too! Turns out he's fallen under the spell of a succubus who loves to fatten up humans with her delicious cooking.  Can Elfuda protect her human friend, or will they both succumb to their cravings?