User blog comment:Omega natsu2/Fairy Tail Zero: Night of Embarking, Review./@comment-5303512-20140913194028/@comment-4933386-20140914024132

There's a chance that she is similar to what Mavis is to the Fairy Tail guild.

Only guild members can see her and no one else. Soooo because Mavis and Zeira is in Red Lizard, she can naturally see her as real, and because the others don't have the guild mark, they don't see her at all.