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The Valanginian period is marked by significant events, including the earliest perturbations of the global carbon cycle and the initial emplacement of large igneous provinces on land. Recent years have seen the ratification of the global boundary stratotype sections and points (GSSPs) for the Valanginian and Hauterivian stages, reflecting increased stratigraphic and palaeoenvironmental research on the Valanginian. However, paleoceanographic information remains limited for the Early Cretaceous Panthalassa, which was the largest ocean during early Cretaceous. In Northeast Japan, Lower Cretaceous marine sequences, formed in the northwest region of Panthalassa along the northeastern margin of Eurasia, are exposed intermittently. These sequences have been challenging to date accurately due to the limited availability of age-diagnostic fossils. We establish new global stratigraphic correlations using U–Pb zircon ages from tuffs and carbon isotope stratigraphy for the Lower Cretaceous formations of the Karakuwa and Oshima Groups in Northeast Japan. We identify the Berriasian/Valanginian boundary and the Weissert Event within these strata. In addition, we recognize a potential stratigraphic level for the Valanginian/Hauterivian boundary. Notably, the Weissert Event interval within these sequences does not exhibit the significant lithological changes, such as the intercalation of black shales or a decrease in bioturbation observed elsewhere . By contrast, observed lithological changes are indicative of regional tectonics, including large-scale sinistral strike-slip movement and subsequent ridge subduction along the active continental margin of Eurasia.