A water nymph appearing in volumes one and two that lives in the pond near Dong-Young's school vacation spot. A legend surrounds the pond, saying that a beautiful nymph lived there. One rainy day, a young man came to the pond and kept crying out a girls name. The nymph fell in love with the man and came to him, telling him "You are handsome and kindhearted. You deserve to be loved.". Happy, he stayed with her for some days, bringing her a hair clip and talking to her, thinking them friends. However, one day he came by and said he was going to marry the girl he loved, while running away. The nymph panicked and called his name, reaching out to him and saying she could not leave her pond. Not knowing that humans cannot live underwater,she took him in her arms and accidentally drowned her lover in an attempt to live with him forever in her submerged palace. Thinking he was only ill, she called on the advice of a mysterious Bi-Wal look-a-like (revealed later to be Bi-Wal's brother) who told her to call an angel from Heaven to her pond and use its sacrificed blood to "cure" her lover. The water nymph seizes the opportunity to lure Dong-Young into her home for the sacrifice. However, upon finding his love interest kidnapped, Bi-Wal enters the underwater lair to rescue Dong-Young. Before killing the nymph, he reveals to her that she in fact, killed her lover and that no sacrifice would bring him back. Bi-Wal summons a sword during the battle, which Dong-young sees. Bi-wal then deletes her memory of the events and takes her back to the resort.
(It seems as though the water nymph has a tail in water, but can give herself legs when needed, as when she first lures Dong-young, she walks to her room in the resort, but when she has her walk into the pond and Doh-Hyun interrupts her, they show a tail retreating into the water.)