Isohime (磯姫) is a sea witch likes to rip humans off with her trade and can bargain very well. She has a special clairvoyance which can see what regular eyes cannot, such as the Dragon King's eye which was inside Nanami.
She's very cunning and tricky but also knows when to give up and run away. She can fool people with words to buy from her magical items that may or may not work. She has a cackling laugh and often seeks power and long life when the opportunity presents itself. However, she has the tendency to avoid yokai and magical creatures like herself and instead targets humans only.
When Nanami had traveled back to the past, she first met Isohime who was shrouded in a windbreaker, which she offers to Nanami in trade for the Dragon King's eye inside her. However, Mizuki appears and Isohime runs away.