During a full moon in May, the arrival of triplet princesses brings joy to a lonely King and Queen. The kingdom of Harmony shares in their happiness and gives an abundance of gifts to the princesses every year for their birthdays. As they become older, the princesses become selfish and demanding, and on their eighteenth birthday, their demands for their gifts makes the kingdom of Harmony leave and go on a vacation. The King and Queen become so upset and come up with a clever plan to change their daughters' bad behaviors. The princesses have to pack their favorite possessions and set sail to find and help others in need. By doing this, the King and Queen hope that when they return, they will have experienced kindness and joy in their hearts.