12 years have passed since the end of the war. Mayumi Sugimoto, who lost her father in the atomic bombing, lived with her sick mother in the suburbs of Hiroshima. However, her house was burned down and her sick mother died, leaving her alone and she went to live with her aunt in Tokyo.
All Mayumi has left is her mother's keepsake ring. But the ring holds a big secret. It can tell her where is the treasure hided by her father. A man named Kurohara is pursuing Mayumi, hoping to steal the ring.
When Mayumi returns to Hiroshima to visit her best friend Sachiko, who has been hospitalized due to radiation sickness, she was kidnapped by Kurohara's men and her ring is stolen. Mayumi is in the depths of despair after her best friend Sachiko dies and her ring is stolen from her. Then, a mysterious man with a bandaged face appears before her...