On Red Sand, canals split the city in two: the right bank's orbital towers where the rich own starships, and the left bank's tin-shack slums. Paddleboard racer Ophina competes desperately and keeps close to Lucien, CEO of the Thorne Starship Group, to earn money for starving orphans—while fighting to reclaim her mother's gold-mining star, seized by her father and stepmother. Lucien must marry Lina of the Reed family for a resource deal. Ophina never expects he's her stepsister's fiancé.