Utamaro's "Twelve Hours of the Green Houses" (Seirō Jūnitoki Tsuzuki (青楼十二時 続)), often known as "Twelve Hours in Yoshiwara", was originally produced around 1794 by the famous publisher Tsutaya Jūzaburō. The series features beautiful courtesans of the Yoshiwara pleasure quarters going about daily (and nightly) tasks, with each print representing a different time of day. The prints' titles, "Hour of the Dragon", "Hour of the Ox", and so on, reflect the traditional Japanese method of telling time using the zodiac. Despite the title, the series actually depicts 24 hours, as the day is broken into 12 2-hour groups.

The zodiac and their corresponding (approximate) hours are included below and in our descriptions of each print in the series:

Hour of the Rat: 23:00 - 1:00
Hour of the Ox: 1:00 - 3:00
Hour of the Tiger: 3:00 - 5:00
Hour of the Hare: 5:00 - 7:00
Hour of the Dragon: 7:00 - 9:00
Hour of the Snake: 9:00 - 11:00
Hour of the Horse: 11:00 - 13:00
Hour of the Sheep: 13:00 - 15:00
Hour of the Monkey: 15:00 - 17:00
Hour of the Cockerel: 17:00 - 19:00
Hour of the Dog: 19:00 - 21:00
Hour of the Boar: 21:00 - 23:00

According to Wikipedia, "Seirō (青楼, "green house[s]") refers to the yūkaku licensed pleasure quarters — specifically Yoshiwara. The term seirō originated in Chinese to denote a pavilion in which a nobleman kept a mistress; in Utamaro's time it referred to Yoshiwara's most privileged pleasure houses". Tiny flakes of gold leaf have been scattered on the backgrounds of all of the prints in this series, probably to emulate the decadence of such houses.

Unlike Utamaro's "portrait" prints showing figures from the bust upwards (okubi-e), the courtesans are depicted from head to toe, allowing the viewer to admire the beauty of their outfits in full. In this way Utamaro "zooms out" to let us see more detailed images of the lives of the glamorous courtesans of Edo. This reproduction set of Utamaro's famous series was published by Adachi in the 1980s.