Birthdays in the City of Masks

Located in the Shield region, the City of Masks has earned its name for the custom of every adult wearing some sort of face covering at all times in public. The masks vary wildly depending on one's income and status, with the poorest using ratty old cloth and the wealthiest favoring delicate porcelain or precious metals. Masks are first given to people at the age of seven, and must cover at least half the face, though there is broad latitude in which half and how the mask is shaped. One thing that is universal, however, is the celebration of subsequent birthdays and how the masks are changed.
While masks must occasionally be replaced, any markings or carvings upon them are transferred over. When first given, the mask will have markings indicating the position of important celestial bodies for reference inscribed on the right cheek (if available). Each birthday after, another celestial marking is inscribed, seemingly at random to outsiders but in all cases following specific guidelines. It may be the moon phase one year or the location of the gods' old home at midnight another year, sometimes the angle of the Girdle... the priesthood within the city dutifully attends every birthday celebration to ensure the markings are made. These tell the story of the mask wearer's soul, and denizens of the city can tell a great deal about a person based on these inscriptions. Despite the gravity of the situation, birthdays are always cause for celebration, and under the pretense of honoring the visiting priest with hospitality, special cakes are made (often sweet, though the exact cake varies from season to season) and spirits are uncorked for the occasion. The priest will often give the birthday celebrant a gift (though the family is expected to send this along to the temple in advance), and incense is burned when available.