Provenance — where it came from
Dasai means uncool, unfashionable, hopelessly out of style. It appeared among young people around the 1970s. Where it came from, nobody knows for certain. One popular folk story says it comes from mocking the neighboring prefecture of Saitama — da from datte Saitama (“because it’s Saitama”). This theory is itself a joke, and probably false. The word’s true origin is simply lost.
Here is the interesting part. In the 1980s, dasai stood opposite nau-i (№ 001), the word for everything new and cool. Then the 1980s ended, and nau-i died. Dasai did not. New words for “cool” kept arriving — and kept dying — while dasai stayed at its post, marking each of them as uncool on their way out.
Words of praise burn bright and burn out. Words of dismissal, it seems, are built to last. By the 2020s, dasai had been calling things uncool for half a century — never once sounding dated itself.
Field notes — how it’s used
その服、ダサくない？
sono fuku, dasakunai?
“Aren’t those clothes… uncool?” — as devastating in the 2020s as in the 1980s.