Figure S1. Epidermal hyperplasia in reddened skin. (a) Gross appearance of reddened facial skin compared with non‐reddened skin. Dilation of capillary vessels was frequently found in facial reddened skin (arrows) as compared with non‐reddened skin. (b) The average age was not different between the two groups, (c) but the skin color defined as the color space (L*a*b*), which is also known as CIELAB, revealed that the indicator for redness, a* was significantly increased, whereas the indicator for brightness, L* was decreased in the facial skin of reddened skin. (d) Hematoxylin–eosin staining of skin sections revealed that reddened skin showed characteristics of epidermal hyperplasia compared with non‐reddened skin (scale bars, 100 μm). (e) Moreover, immunofluorescence analysis for the proliferation marker Ki‐67 (green) demonstrated that an increased number of Ki‐67‐positive cells were found in the epidermis of reddened skin compared with non‐reddened skin.