Noble gas
group of chemical elements tend to be chemically inert and thus form odorless, colorless, monatomic gases with low reactivity; consists of helium, neon, argon, krypton, xenon, radon, and possibly oganesson
Was the Japanese street aesthetic once illuminated by noble gasses?
Japan was known for their use of brightly lit businesses and signage. The signs in Japan were lit with neon for a long time.
What were the signs in Japan known for in the past? Were noble gasses the reason behind #1?