In this essay I analyse the dissent embodied by the Japanese science fiction of the 70s, and in particular two works of Komatsu Sakyō (1931-2011): ‘Nihon chinbotsu’ (Japan sinks, 1973) and ‘Jikan ējento’ (Time agents, 1975). The former – probably the most noted of Komatsu’s novels – conveys a strong political dissent through the chronicle of a natural disaster in which Japan sinks into the Pacific Ocean. While such sinking can be thought of as a metaphor for the current state of the foreign policy of Japan, which was bound to United States’ one through the Security Treaty, the novel stigmatizes the ineptness of Japanese politicians who try to conceal the forthcoming crisis. ‘Jikan ējento’ is a short novel based on the subgenre of alternative history with a tinge of humour. Here, again, Japan’s national and foreign policy is indirectly criticized, while the novel provides a ground for reflecting about the several choices that can be made in a given situation.