Around 700 stalls line the street during the annual Setagaya Boroichi, a venerable flea market that's been going on for more than 430 years now. Held twice a year – on December 15-16 and again on January 15-16 – the event attracts tens of thousands of visitors, making it one of the highlights on Setagaya's yearly calendar.
The main area of the market is along Boroichi-dori, a street which centres around the Setagaya Daikan Yashiki, the old, thatched-roof local magistrate’s residence. We’d recommend hopping off the train at Setagaya Station on the Setagaya Line, walking along Boroichi-dori, and then leaving from Kamimachi Station. And if you don't mind the long lines, it's worth sampling one of the market's popular daikan mochi rice cakes – Boroichi's de facto official snack.
The Setagaya Line is a light railway, and tickets are available as you get on the train or at the platform. You’ll have a smoother trip if you have the fare ready beforehand (¥150 for adults, ¥80 for children).