International Letter Writing Week Issued on October 6, 1966 (Showa 41) In October 1966, the International Letter Writing Week stamp was issued.This is an international week that contributes to world peace through mutual understanding through correspondence. It is set every year for a week from October 9, the date of formation of the Universal Postal Union (UPU). The stamp is designed by the ukiyo-e artist "Katsushika Hokusai" 　the 36 views of Mt. Fuji, "Sumidagawa Sekiya no Sato".