Your search for "gamaguchi" revealed the following:
Fire Emblem Three Houses Doujinshi - Sensei Likes XX (Dimitri x Byleth / Dimitri Alexandre Blaiddyd x Byleth Eisner)
$ 26.95Product details: Dimitri x Byleth / Dimitri Alexandre Blaiddyd x Byleth EisnerByleth has cat ears and a tail! Can Dimitri...