User blog comment:B214/Question and Answers 2/@comment-162.202.198.72-20140122104105/@comment-1359322-20140122133657

Ama no Murakumo no Tsurugi AKA Kusanagi no Tsurugi (Sword of Kusanagi) is a Holy Sword found in the body of the Yamata-No-Orochi, a 8-headed serpent (A Dragon in DxD). Like JJJ said, it's one of the few true Holy Sword and is said to be a Holy Sword on par with Durandal and Excalibur. Any other info is unknown so don't ask too much Otaku. -_-