User blog comment:IamJakuhoRaikoben/Chapter 412: Dance Unto Ishgar, Review./@comment-1359322-20141208144403/@comment-7418318-20141208154207

But what about the date?

The date 7.7.X777 has been made far too important in the story to have no meaning, but going by their words in their introduction in Crocus, Sting and Rogue seem to have "killed" their parents earlier.

If they did the same thing as the other three Dragons, why would Skiadrum and Weisslogia do so early, instead of doing it on that important day?

And if the bodies of their parents just disappeared, wouldn't that also raise the suspicion of Sting and Rogue? We've seen an entire Dragon Graveyard full of evidence that Dragons leave corpses behind when they die.