Home to approximately one tenth of the total citizenry of all of Tokyo's 23 wards, Setagaya houses 800,000 people, the same figure as the population for the entire island of Oahu, Hawaii. At both places, people seem to have come in waves.

Thirty thousand years ago, give or take a millennium, Setagaya's first wave brought late Paleolithic inhabitants who hunted and gathered in this biologically diverse area. Stratum excavations in the upper banks of rivers have yielded some ancient stone tools. Even today, suburban Setagaya's embankments offer up a Paleolithic feast of mushrooms, sweetfish, trout, eel, chestnuts, persimmons, rabbits, tanuki (raccoon dogs) and wild wasabi.

"A healthy environment is one of Setagaya's best features," says 36-year-old Midori Masumoto, born and raised in the ward. "Everyone wants to live here, and once they do, they never leave," she said. I tried to ignore the irony of our conversation taking place at the base of Setagaya's huge Noge Otsuka Kofun, an early fifth-century burial mound, with its surrounding replicas of totemic haniwa (clay sculpture) vessels.