Blood Coral Crystal

The, is a red orb and a precious heirloom passed down to each guardian of the bat yōkai barrier. (Hyakki Mori clan), it gives them the ability to put up a powerful barrier and it stores all the power of each generation of guardians like Shiori's grandfather Taigokumaru and her father Tsukuyomaru. .

History
Shiori was charged with maintaining the barrier for the bat yōkai clan after the death of her father Tsukuyomaru. She is reluctantly given to grandfather Taigokumaru by her mother Shizu in exchange for keeping the village safe from his clan's attacks. Taigokumaru, however, did not honor his promise and continues to attack the village. Shizu and Inuyasha arrive at the yōkai bat cave to confront. Shiori used the crystal to protect Tsukuyomaru from Inuyasha's Kaze no Kizu.

Taigokumaru ordered hi clan to destroy the village to remove any distractions from Shiori's duty. Shiori continued to put up a barrier around Taigokumaru with the crystal. The protected him from all of Inuyasha's attacks. She expelled Taigokumaru from her barrier when she learned that he killed her father. Inuyasha was able to kill Taigokumaru with the Bakuryūha.

Shiori presented the crystal to Inuyasha so he could have Tessaiga absorb its power. The crystal suddenly emitted a demonic aura that presented a danger to Shiori. The spirit of Taigokumaru appeared with the intension of killing Shiori. She was protected by the spirit of her father and a barrier appeared just as Taigokumaru attacked. He was weakened from the barrier and was destroyed by Inuyasha for good.

The crystal split in half and became clear after Inuyasha destroyed Taigokumaru's spirit. All of its powers were then absorbed into Tessaiga.

Powers & Abilities

 * Impenetrable Barrier: The crystal can erect a barrier so strong it could withstand the Kaze no Kizu (Wind scar) easily and even withstand the backlash wave though it was temporarily weakened by the latter. It is said that the barriers created by the Demon Bat Clan are considered to be impenetrable though the barrier can only held up by one member of the clan at the time which wanes with age and when passed to the next then the ability is lost altogether. Should the need arise, the crystal can project a small personal barrier around itself if it's threatened.
 * Demonic Aura: If the crystal is threatened it can emit large amount of demonic power that mesmerizes a hanyō or weak demon holding it and burn a human if they attempt to grab hold of it.
 * Soul Collection: It is also said that this crystal houses the spirits of the previous generations of the bat barrier guardians of the clan and thus can release the spirit of a previous guardian if its existence is threatened such as Taigokumaru's soul reappearing after Shiori suggested that Inuyasha destroy the crystal. Though there are chances when a previous guardian spirit can escape it on its own such as Tsukuyomaru in order to protect his wife and daughter.