Kusanagi-no-Tsurugi, is one of the three Go-Shin Tai of the Japanese Empire, one of the three sacred treasures that symbolize the Imperial throne. The sword was taken from the Dragon-King of the sea by Yamata no Orochi, who lost it later when Susanoo removed it from his tail. Because it is one of the Go-Shin Tai, it can only be weilded by the Emperor of Japan. The sword was lost sometime in the 12th century.

The sword's original name was Ama-no-Murakumo-no-tsurugi, which means "heavenly gathering of clouds sword." It recieved its current name, "Grass Cutting Sword" when it was used by Yamato Takeru to cut grass to make an escape route and shield him from surrounding fire in one of the Ainu subjugation campaigns.