User blog comment:Miskos3/Fairy Tail Episode 234: Tartarus arc Prologue: The Nine Demon Gates, Review/@comment-5303512-20150523164409/@comment-7418318-20150524104557

No one actually outright said that, but there was a tweet from Mashima which strongly indicates it [over here]. You'll need to scroll down a bit to get to the discussion started by Chaos.