After Natsume returned Amana’s name, she accused him of stealing her ring.  He has three days to find and return it before she burns down his house.  To make matters worse, the ring is trapped in the hair of a migratory youkai, and Nyanko-sensei is unable to use his powers.
It's supposedly an antidote 
for youkai poison.
Cura el veneno de los ayakashi.
Es para curar el veneno de los ayakashi.
Parece que é antídoto pra veneno de youkai.