Half-light radii R_1/2 in pc (red and green for 13 and 8.5 μm, respectively), plotted against UV luminosity L, which is defined as 6 νL_ν(5500 Å) (Kishimoto et al. 2007). The red and green dotted lines are power-law fit to R_1/2 at 13 μm (∝ L^{0.01 ± 0.07}) and 8.5 μm (∝ L^{0.21 ± 0.05}), respectively. In this physical scale, these mid-IR radii increase with luminosity much slower than L^1/2, or almost constant at 13 μm. Thin-ring radii at 2.2 μm also in pc are plotted in purple for the KI-observed sample. Plotted with gray plus signs are the near-IR reverberation radii (Suganuma et al. 2006 and references therein), with the black dotted line showing their L^1/2 fit. This fit is the definition of the inner radius R_in in this paper.