Yasakani no Magatama (八坂ノ勾玉 Yasakani no Magatama) is one of Three Regalia that can only be found in Mt. Fuji's Haunted Ground. If someone possesses the three of them, that person becomes Japan's King.
Out of the Three Regalia, Yasakani no Magatama represents the supporting element of Japan's King. With it, the user gains increased movement through teleportation and portal creation.
Previously owned by Tsukuyomi, by unknown reasons the magatama was found in Mt. Fuji's Haunted Ground. During the Treasure Hunting, Ilyaelia finds Yata no Kagami and the magatama. During Kazuki's fight with Ikōsai Aisu, Ilyaelia interrupts the fight and gives her Yata no Kagami while she kept the magatama. When Aisu retreated, Ilya fights Kazuki, resulting in her defeat. When he was about to deal the final blow, Ilya escaped with the magatama and engaged in a fight with Regina. She fled again and gave the magatama to Aisu.
The magatama was later used by Aisu to retrieve Hel from Kazuki's attack, and was used during her battle against him to determine who will be Japan's King. After the fight with Aisu for who will be Japans king which she lost the Magatama along side Yata no Kagami was given to Kazuki who won the duel.
Yasakani no Magatama's main ability is for support. It can be used to retrieve someone from the battle as long as the user knows the target's presence, create portals that leads to another dimension and appear in another place in the world.
- Kaicho Kaikon ― Kamiwatari no Mon: One of the incantations of Yasakani no Magatama. The magatama enlarges and creates a portal to another dimension. The user can enter and exit in another place to the user's desires. It is useful for surprise attacks. If used in the middle of a battle, the user and the opponent cannot detect the other's presence and magic power if they are in different dimensions.
- Kaicho Kaikon ― Yachimon Shibari: Another one of Yasakani no Magatama's incantations. The magatama enlarges and then wraps around the enemy binding them.