This chapter explores very long-term trends in socio-ecological sustainability in the Japanese Islands with a particular focus on the Neolithic Jōmon period (c. 14,500–900 BC). Sustainability is analyzed as a means of problem-solving rather than as a default result of environmental abundance. Previous research has proposed three main outcomes of long-term problem-solving: collapse, complexity, and resilience through simplification. Despite many examples of sudden social change in the Jōmon period, collapse may have been confined to the aftermath of major natural disasters such as VEI-7 volcanic eruptions. Although it has been argued that increasing complexity was a common response to social and ecological problems, the drawn-out process of Neolithization in the Japanese archipelago suggests that early human societies were reluctant to choose Neolithic complexity when alternatives existed. Jōmon Japan presents perhaps the most contested trajectory towards Neolithization anywhere in Eurasia.