William The cloth edging on tatami is called “heri” (畳の縁). It’s etiquette not to step on heri when walking on tatami to prevent wear, but sitting on it is fine.
Our friend Victoria Yoshimura noticed that the heri on the benches at Kumamoto Airport have a familiar logo.
Update: Those interested in Kumamon-themed igusa products can contact the Yatsushiro Igusa Kyokai: https://igusa-tatami.jp/news/6079/ Fun fact! - Yatsushiro produces 90% of Japan’s igusa.