Illustration of Edo Shin-Yoshiwara Hassaku Shiromuku (Edo Shin-Yoshiwara Hassaku Shiromuku no Zu)
Painted by Utagawa Kunisada I Around 1822-1823 (Bunsei 5 to 6) Tokyo Shiryō Collection 0791-C17

Hassaku, the first day of the eighth month of the lunar calendar, was the day when Tokugawa Ieyasu set up the shogunate in Edo and so the event held on this day was given the greatest importance during the Edo period.

On the first day of the eighth month of the lunar calendar, the ceremony of Hassaku took place at Edo Castle. It was upon this day in the year 1590 (18th year of Tenshō) that Ieyasu Tokugawa set up the government in Edo and so this day was of the utmost importance to the shogunate. On ‘Itsutsudoki' (around 7 to 8 in the morning), all the daimyōs stood in waiting for the Shōgun wearing white katabira, unlined linen kimonos, and long ceremonial hakamas. The Shōgun wore the same ceremonial white dress and greeted the daimyōs and hatamotos. The white katabira became the symbol for Hassaku.
There were no events in particular for the common people on this day, but in Yoshiwara, there was a custom to mimic samurai society in a big way and on this day the 'pleasure women' all wore shiromuku (all-white kimonos) and cariied out an oiran (prostitute-courtesans) procession along the main streets.