Theresa, mistreated by her stepmother and stepsister, lives like a servant in her own home. However, she possesses a strange and special power: she can see and pull out the metaphorical "thorns" that are stuck in people's hearts, healing their emotional wounds. One day, a mysterious young man named Shiga appears before her. He makes a unique request: "I want you to pull out the spear that was stuck in an evil dragon a thousand years ago." This wish marks the beginning of a grand journey that will dramatically change Theresa's destiny.