Yōkai bat cave

The  was a seaside cave used by a clan of Bat yōkai, formerly led by Taigokumaru. It was protected by a powerful barrier, projected by the youngest member of the leader's line, using the Blood Coral Crystal. As the current leader ages, their ability to project a barrier diminishes, so they turn over guardianship to the younger family member.

History
Taigokumaru left this duty to his son, Tsukuyomaru, until he suggested that their clan stop feeding on humans. After this quarrel, Taigokumaru killed his son and forced Tsukuyomaru's human lover, Shizu, to give up her and Tsukuyomaru's hanyō daughter Shiori, so she could put up the barrier for the clan instead. Eventually, however, Inuyasha came across the cave with the intention of killing its guardian in his attempt to grant his sword's ability to break barriers.

Inuyasha and Shizu confronted Taigokumaru at the cave to save Shiori. Taigokumaru refused to relinquish Shiori. Inuyasha tried to destroy him with the Kaze no Kizu, but the barrier around the cave protected Taigokumaru. He retaliated with a sonic blast. Shiori begged her grandfather to spare her mother if she fulfilled her duty of maintaining the barrier. Inuyasha and Shizu retreated after Taigokumaru claimed that Shori would never be accepted back into her village due to her yōkai heritage.

Taigokumaru decided to have the yōkai bats attack the village as a way to remove all distractions from Shiroi. The entire clan under, including Taigokumaru himself, was killed and the cave became uninhabited. The Blood Coral Crystal was destroyed, and no one would have been able to put up a barrier anyway.