User blog comment:FairyRaven/Fairy Tail Chapter 394: Juvia vs. Keith, Review and Commentary/@comment-24490201-20140725145014/@comment-173.215.2.142-20140725165415

It doesn't say that it's NOT temporary either. The whole tattoo thing is what is making people think that it might be, like with Kana receiving Fairy Glitter.

Personally, I hope it's permanent, too, even though a lot of people are saying it's bull crap either way. Honestly, he's earned it; he's already proven he can do it TWICE. Though I do hope that he does have to work to perfect it...