Light curve of KMT-2021-BLG-1968 in the region of the anomaly. The curves drawn over the data points are 2L1S, 1L2S, and PSPL models, and the lower four panels show the residuals from the individual models. The three insets in the top panel show the lens-system configurations of the close and wide 2L1S solutions and the 1L2S solution. For each 2L1S configuration, the cuspy red figure represents the caustic, and the arrowed line indicates the source trajectory. For the 1L2S configuration, the small filled dot represents the lens position, and the arrowed lines marked in red and blue represent the trajectories of the primary and secondary source stars, respectively.