Futunomitama no Turugi

The Futunomitama no Turugi (フツノミタマの剣, Futsunomitama no Tsurugi; the Futsunomitama Sword in the English manga, the Antiquity in the English anime) is a stone sword that is owned by the Asakura Family''

About
Futunomitama no Turugi is a red stone sword that has been a treasure of the Asakura Family for many generations. According to Asakura Hao, it was once owned by a sword god and even though it's only made of rock, it is the perfect medium to create a sword oversoul. The sword which slumbers in a storage room of the Asakura Family always creates a stir in the world when it surfaces because it's a national treasure.

It was used by Asakura Yohken to kill his ancestor Hao, when he reincarnated into the Patch Tribe. Five hundred years later it was used by Asakura Yoh as a a secondary medium for his Over Soul during the second rounds of the Shaman Fight. Yoh's son, Asakura Hana would eventually inherit it and used as his main medium for his Over Soul.

Trivia

 * The Kanji for sword, 剣, is usually spelled Tsurugi in rōmaji, but in the Kang Zeng Bang Shaman Files it is written as Turugi. It is unknown if this is a mistake or intentional.