Hayami Shun is an ordinary worker at a trading company when he found himself floating in the sea in another world after walking out of the building. He was resigned to his fate of drowning when he was saved by a creature which had the upper body of a horse and a lower body of fish, a Kelpie who called herself Requaire. In this other world which had just entered the age of seafaring, Shun uses his in-depth knowledge of trading to make a name for himself. Along with the mysterious and expressive Kelpie, Requaire, will Shun be able to rise up in the market of trading!?