The popularity of Klarna installment payments is profoundly influencing the design philosophy and R&D direction of sex doll products. To adapt to the installment payment model, manufacturers are rethinking product lifecycles and value propositions. The newly launched Klarna sex doll series features a significantly enhanced modular design, allowing users to extend the lifespan of the product through future upgrades. This design concept aligns with the concept of installment payments, allowing consumers to purchase a basic sex doll torso with a low initial investment and then gradually add functional modules as needed. Industrial designers revealed that the torso sex dolls, developed specifically for Klarna installment users, have undergone significant improvements in interface standardization to ensure compatibility with future accessories.