Revenge of the Pearl Queen.

Kizaki, an upstart at a trading company has one more assignment for the day before meeting his lovely girlfriend, Natsuki for a date. Little does he know that he's walking straight into a trap set up by his boss, Asanuma and his murderous right hand man. The next day Kizaki finds himself framed for the murder of the company president, and the robbing of the company safe. Natsuki innocently waves goodbye to her loved ones as the boat sails only find herself caught in Asanuma's evil scheming and the object of his lust. In a desperate attempt to escape, she falls to the watery depths. When we next see her she has washed ashore like a siren in the nude on a deserted island inhabited by five castaways who fight each other for her. She learns there's a rich wealth of clams underwater and eventually comes into a large fortune in pearls. Once rescued, she returns to Japan with revenge on her mind.