Using the provided reference image as the character base, keep the same chibi 3D figure, outfit, hairstyle, lighting, plain white background, and overall composition unchanged, but modify only the facial expression according to FACS action units: {argument name="FACS action units" default="AU1C + AU2C + AU5D + AU26C"}. Preserve the reference image’s square face-obscuring block in the same central position and regenerate the image cleanly with the same toy-like render quality.