Used in Recipes
Obtained from Desynthesis
How to Obtain
The Totsuka-no-Tsurugi (十拳剣, lit. "Ten-hands Long Sword"), Ama-no-Habakiri (天羽々斬, lit. "Slash of Heavenly Wings"), Ame-no-Ohabari (天の尾羽張, lit. "Tail-feathers of Heaven"), or Worochi-no-Aramasa is the legendary sword of the Shinto god Susanoo. It was also the sword used by Izanagi to kill his offspring, Kagu-tsuchi.
After the sword's owner, Susanoo, was banished from heaven by the reason of killing one of Amaterasu´s Attendants and destroying her ricefields, he descended to the Province of Izumo where he met Ashinazuchi, an elderly man who told him that the Yamato-no-Orochi ("Eight Branched Serpent"), who had consumed seven of his eight daughters, was coming soon to eat the last one: Kushinada-hime. Susanoo decided to help the family and investigated about the creature, soon he begged Ashinazuchi permission to marry Kushinada-hime, which was granted; having his plan ready, he transformed his wife into a comb so he could have her near in the battle.
As the great snake came, it put each one of his eight heads trough the gates the god built, searching for the daughter; as a bait the god had put big amounts of sake after each gate, the snake took the bait and got drunk; having an easy chance, Susanoo took the Worochi no Ara-masa and cut every head off the snake, proceeding with the tails, in the fourth one he found an exceptionally great sword, the Kusanagi-no-Tsurugi. Having the sword in his hands he returned to the heaven offering the sword as a reconciliation gift to his sister Amaterasu.
Taken (and slightly edited) from Wikipedia.