The δ18O values of planktic and benthic foraminifera and the species assemblage of planktic foraminifera were investigated at the South High of Shatsky Rise (32°16′N, 158°13′W 2514 m water depth), Northwest Pacific, to understand the oceanographic changes in the Kuroshio Extension (KE) region over the past 23 kyrs. The Δδ18O between species and the abundances of dominant planktic foraminifera species have not changed significantly, suggesting that the subarctic boundary and the subarctic– subtropical transition zone have remained north of study site, while the study site itself has been under the influence of KE. Nevertheless, we observe the increased abundances of foraminiferal taxa that populated the subarctic– subtropical transition zone during the last glacial maximum (LGM), indicating the input of transition zone water through the KE by its meandering and the generation of cold-core rings along the KE. Such unstable surface environment is most pronounced along the main axis of the KE, it could have been induced by the southward displacement of the KE main axis to the vicinity of the study site, in tandem with the overall southward displacement of the Kuroshio– Oyashio Extension system during the LGM. The input of transition-zone water mass has also increased during the deglacial Northern Hemisphere cold events (i.e., Heinrich Stadial 1 and the Younger Dryas), suggesting that the strengthenoceanographic changes in the Kuroshio Extension (KE) region over the past 23 kyrs. The Δδ18O between species and the abundances of dominant planktic foraminifera species have not changed significantly, suggesting that the subarctic boundary and the subarctic– subtropical transition zone have remained north of study site, while the study site itself has been under the influence of KE. Nevertheless, we observe the increased abundances of foraminiferal taxa that populated the subarctic– subtropical transition zone during the last glacial maximum (LGM), indicating the input of transition zone water through the KE by its meandering and the generation of cold-core rings along the KE. Such unstable surface environment is most pronounced along the main axis of the KE, it could have been induced by the southward displacement of the KE main axis to the vicinity of the study site, in tandem with the overall southward displacement of the Kuroshio– Oyashio Extension system during the LGM. The input of transition-zone water mass has also increased during the deglacial Northern Hemisphere cold events (i.e., Heinrich Stadial 1 and the Younger Dryas), suggesting that the strengthen