In firm's business activities, it is important to decide target which product market. Actually, firms are misspending great cost and time on marketing. Nevertheless, firms overlap product of the same quality in the market. In the strategic form game of the game theory, there is proposed a solution of the game in which the mediator participates as another party. This paper focuses on k-Implementation, from the viewpoint of the three problems in Nash equilibrium, analysis and consider about the solution of the game. In addition, the authors complement the problem of k-Implementation, and indicate that it is useful in deciding the business strategy.