In the country of Japan, road signs (道路標識, dōro-hyōshiki) are standardized by the "Order on Road Sign, Road Line, and Road Surface Marking (道路標識、区画線及び道路標示に関する命令)" established in 1968 with origins from the Tokyo Metropolitan Police Department's "Order on Standardization of Road Sign" of 1934 and the Home Ministry of Japan's "Order on Road Signs" of 1942. It seems that the previous designs have been used since 1986 after several so-called amendments of order.
They are certainly divided into "Principal Sign" (本標識, hon-hyōshiki) and "Supplemental Sign" (補助標識, hojo-hyōshiki).
Traffic signs or road signs are really signs erected at the side of or above roads to give instructions or provide information to road users. The earliest ancient signs were simple wooden or stone milestones.
古代 (Kodai) ancient
Below are examples of Warning Signs in Japan. Warning signs (警戒標識, keikai-hyōshiki) warn drivers of dangers or situations that they must notice and pay attention to.