User blog comment:Otaku Chick/Otabear's Anime Review: Ep 145/@comment-3075024-20120828023939/@comment-2214433-20120829085525

And Mashima also created the design of all those filler chars + Oracion Seis and Mira's takeover, also he most likely has hands in the story because 'Zentopia incident' has been mentioned in manga by Yukino.