Princess Yoonseul

The mischievous Princess Yoonseul is the daughter of the Dragon King, living in the mysterious Morning Light sea. Despite her father's objections, she is curious and secretly went to the dry land to meet her friend.
She accidentally broke the Netherworld Gate, was transformed into a dog, and then was banished to the dry land. She risked her life to save her friend, which broke the curse, and returned to the Sea Palace.
When the princess returned, her father's worries seemed to disappear. However, she suddenly announces that she wants to bring her dry land friend and marry him, causing the Dragon King to again be bedridden.