Aika is a skilled but impulsive high school student who earns a C-class salvager license yet struggles to find work due to her age and reputation. After advertising her services at school, she is hired by Erika, a wealthy student and leader of the Treasure Hunting Club. What begins as a simple salvage job quickly turns dangerous, leading Aika into a high-stakes mission, a clash in the southern islands, and the mystery surrounding a girl named Karen.