Fairy Heart

Lumen Histoire (光の神話　(ルーメン・イストワール) Hikari no shinwa (Rūmen Isutowāru) lit. Myth of Light) is Fairy Tail's greatest secret.

Description
Lumen Histoire is located in a secret underground room in Fairy Tail's original building. This secret is only known by Fairy Tail's Guild Master and is passed on to the new master successively. Purehito showed it to Makarov when he became Master. Years later, Makarov showed it to Gildarts Clive when he told him that he wanted him to be next master of Fairy Tail. According to Ivan Dreyar, Lumen Histoire is Fairy Tail's darkness while according to Mavis Vermilion, it is Fairy Tail's light.