Kira, who is twelve years old, is intent on wasting her limited pocket money on dolls and other childish things. She lives in poor circumstances, her parents constantly arguing about the shortage of money. Kira is therefore upset by the subject of economics and wishes to avoid it. However, when she twice rescues a stray dog (later named Money by Kira), the dog, in gratitude, reveals its ability to talk. The dog seems to have an in-depth knowledge of economics.