What is shitamachi, besides the title of a major series of Japanese movies starting Friday at Film Forum? Easier to say what it’s not. It’s not tea ceremonies in the imperial gardens. It’s not high fashion in Harajuku or the neon frenzy of Shibuya. It’s definitely not Bill Murray lounging, lost in translation, in the minimalist splendor of the Shinjuku Park Hyatt.

The full name of the 38-film series, “Shitamachi: Tales of Downtown Tokyo,” offers a partial explanation. But having begun as a designation for the eastern, low-lying, more working-class areas of the Japanese capital when it was still called Edo, shitamachi has lost some of its geographic specificity through centuries marked by earthquakes, fires, bombing s and chaotic growth. (Ginza may now be Tokyo’s high-end shopping district, but when Mikio Naruse made “Ginza Cosmetics” in 1951, it was still shitamachi .)

Through time the word has come to refer to quadrants of the mind as much as the map, denoting a rambunctious spirit, an earthy frankness, a mercantile impulse and a healthy grudge against the upper classes who oppress and marginalize. It also implies nostalgia, for better times that might have come before the shogunate, or before World War II, or before the great recession of the early 1990s.