Chosen Hero

Hero (勇者) refers to the counter-part of Demon Lords, an existence that only those who have the blessing of an Elemental of either Light or Darkness can obtain.

As is the case with Demon Lords, Heroes can be divided into those who are known as Hero in title or those who are Heroes as a "Class" as well as those who are neither or both.

Hero's Egg
Hero's Egg (勇者の卵) refers to those who obtain the blessing of an Elemental of Light or Darkness as well as the Spirit Queen. The Hero's Egg is the equivalent of the Demon Lord Seed.

True Hero
True Heroes (真なる勇者) or The One who hatched the Hero's Egg (勇者の卵が孵った者), are those who hatched a Hero's Egg and became an awakened Hero. It is one of the ultimate forms of existence that Humans and Demi-Humans can attain.

Awakened/True Hero is the equivalent of an Awakened/True Demon Lord. They can achieve Divinity that will free them from their mortality completely.

Hero as a Title
Anyone can proclaim themselves a Hero, or be recognized by the masses as a Hero. In either case this "puts fate into motion" and causes this Hero by title to eventually have some sort of predestined connection with a Demon Lord that is unavoidable, though it does not necessarily have to be a hostile relationship.

Trivia

 * Chloe Aubert is the only Hero who ever achieved two Hero's Egg and hatching it because of her incredible circumstances.
 * In the English translations Hero (勇者) is often mixed up with Champion (英雄) because both these terms are usually translated as "Hero" out-of-context. This has sometimes caused "Champions" in the English translation of the series to be mixed up with Heroes. Likewise the term Heroic King (英雄王) also refers to Champions and not Heroes.

Reference
pt-br:Herói Герой