This study attempts to examine the convergence development of the marine fishery (MF) and marine tourism (MT) industries of Japan through the theory of industrial relevance. First, the current MF and MT situation in Japan is introduced to analyze the mechanism of the integration of the two industries. Second, a Vector Autoregression Model (VAR) is built to examine the relationship between MF and MT. In addition, the shock potential contributions of the MF and MT industries are identified using impulse response and variance decomposition. Results show that the impact of MF on MT is more significant than that of MT on MF. However, the interaction between MF and MT tends to stabilize in the long run. Third, the industrial integration case of Japan’s Himakajima Island is selected to analyze the MF and MT integration mechanism. The integration of MF and MT can reduce transaction costs, make full use of labor, and promote the development of the local economy. Therefore, attention should be paid to the integration of the MF and MT industries, rather than partial implementation, to balance the development of the marine economy. Finally, relevant suggestions and measures are presented for marine industry transformation and upgrading, industrial integration, and green ecological development.