Harmonica Yokocho actually started out as a black market in the post-war years but has since transformed into a small network of about 100 bars and restaurants (the name comes from the fact that the narrow entrances to the yokocho look like the holes in a harmonica from the main street). An ideal place for a drink if you are visiting in the evening.
Directions
A 1-minute walk from Kichijoji Station (turn left from the North Exit). Turn left out of the ticket gates and Harmonic Yokocho will be a short walk down the road on the right