The Setagaya Boro-ichi (世田谷ボロ市) is a large open-air market held near Tokyu Setagaya Line Station Kamimachi Station from 15th to 16th of December and January. About 700 to 800 stalls sell various things at this fair.
The predecessor of the Setagaya Boro-ichi was founded here in 1578 as a fair held six times a month by Hojo Ujimasa, the then ruler of the Kanto region who lived in present-day Odawara City, Kanagawa Prefecture, since this area was strategically important - there was a castle and a major highway connecting Edo (modern-day Tokyo) and Odawara crossing the area. But after the fall of the Hojo clan and the establishment of Tokugawa Shogunate at Edo, this area lost its strategic importance and became an ordinary farming village. The fair also changed shape in the process and became a year-end market held on December 15. In those days, new year goods, farming tools and necessities were its main merchandise.
When the feudal times came to an end, the Western calender was introduced in 1873, so the new year became about a month early from before. But people living in rural areas celebrated the new year based on the old calender as before, so the market began to be held on January 15 as well.
Nowadays, this open-air market is basically just a large flea market consisting of 700 to 800 stalls.
These are photos taken in the morning of December 15th, 2017. Though it was not a national holiday, many people were there from the morning.
Every five years, there's a procession called Daikan Gyoretsu on the 15th of December and January. This procession imitates the inspection tour conducted by the local governor to oversee the fair in the Edo period.
Access: a few minutes walk from Tokyu Setagaya Line Station Kamimachi Sta.