User blog comment:IamJakuhoRaikoben/Chapter 371: Tartarus Arc: Part 2 - Song of the Heavenly Dragon, Review./@comment-4999650-20140215180641

I believe it has been said that the titles that are along the lines of "Tartarus Arc Part 1" or w.e are not the specific titles of that chapter but for the next few subsequent chapters. Meaning, this chapter may not be relevant to a Heavenly Dragon but the next few might incorporate it. Plus, I always thought it was a mistranslation (like Starfrost Essence being Drop of Time) so let's just wait it out...