Recent K–Ar ages from the Abukuma Metamorphic Rocks in the Gosaisho–Takanuki area provide a chronological anchor for re-evaluating mid-Cretaceous low-P/T metamorphism and plutonism along the East Asian margin. The Gosaisho–Takanuki, Takato–Shiojiri, Iwakuni–Yanai, and Higo areas record broadly coeval low-P/T metamorphism and Cretaceous plutonism and collectively define a margin-scale plutono-metamorphic system. We propose a testable geodynamic model in which slab rollback, or a related change in subduction geometry, promoted asthenospheric upwelling and mantle-wedge heating, increased slab-derived fluid and melt fluxes, and ultimately contributed to distinctive magmatism, granitoid generation, and regional low-P/T metamorphism. Magmatic features potentially related to rollback are particularly well documented in SW Japan, including high-Nb basaltic magmas, adakites, high-Mg andesites, and evidence for slab-derived components in Cretaceous granitoids. Further evaluation of this hypothesis requires integrated petrological, geochronological, and geochemical datasets from less well-studied segments of the proposed system. In particular, establishing links among mafic to intermediate magmatism, granitoid generation, and regional low-P/T metamorphism is essential for evaluating the scale and mechanism of this tectono-thermal system.