Yashita Tribe lived in ToTai Island around 14th to 16th centuries
This is a story from the Yashita Tribe during the plague causing many people to die. They believed it was caused by a curse of bear spirit. 
In order to get rid of the curse they sacrificed 11 girls to the secret pond.    

Yashita Tribe girls found a sick cave seal.  They tried to nurture him back to life but he dies. 
So they decided to have a cave seal BBQ, but you know what?! Cave seal was infected with mushroom!!!