The Japanese government’s decision to discharge nuclear wastewater from the Fukushima Daiichi Nuclear Power Plant into the sea on April 13, 2021 has aroused widespread concern around the world. The Japanese people, especially the fishermen, have expressed their long and strong dissatisfaction with this decision. Motivated by this background, this paper discusses an evolutionary game considering the impact of participants’ emotions to explore the evolutionary stable strategies of both the Japanese government and Japanese fishermen. The results show that (i) The evolutionary stability strategies of the two sides of the game are different under different emotion combinations. Under the optimism of the fishermen, the fishermen’s decision making is irrational, and the equilibrium strategy of the game between the two sides is not conducive to the fishermen. (ii) The emotions of the players will not only affect their own strategic choices but also affect the strategic choice intentions of other players. (iii) Reducing the cost of nuclear wastewater treatment is currently the most feasible way to reduce the probability of the Japanese government’s discharge policy. Under the premise that the government chooses to discharge, no matter what the fishermen’s emotions are, it is the fishermen’s dominant strategy to strive for more subsidies for their own interests. The abovementioned findings can provide a decision-making reference for the Japanese government to formulate discharge strategies and for Japanese fishermen to protect their rights and interests.