Thread:CureHibiki/@comment-28157842-20170121090337/@comment-31119526-20170319104244

It's probably from 増える (fueru). From the few screenshots I saw last night, that's exactly what ep.07's monster did. Might also be related to the kanji 風 (kaze/fuu), looking at that floatation ring it's wearing, but that's just a wild guess atm.