Yōkai bat cave

The Yōkai bat cave is a seaside cave used by a clan of yōkai bats, formerly led by Taigokumaru. It is 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. 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, in his attempt to strengthen his sword with the ability to break barriers, Inuyasha confronted Taigokumaru and saved Shiori. The entire clan under Taigokumaru's command, including Taigokumaru himself, dead the cave became uninhabited. The blood coral crystal was destroyed, and no one would have been able to put up a barrier anyway.