International Letter Writing Week Issued on October 6, 1977 (Showa 52) In October 1977, 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 stamps are designed with "Kachoz (Japanese paintings depicting birds and flowers") drawn by Hasegawa Shinshun, a painter from the Momoyama-Edo period.