The Sekai1) Bicycle Company was started in Seattle in 1971 by Glenn Tamura, who owned the local Velocipede Bike Shop 2)3) and imported their bicycles from Japan. Sekai was eventually purchaced by Norco of Canada in 1983, who discontinued the Sekai brand by 1990 4). All Sekai mountain bikes were designed by Norco and manufactured in Japan or Taiwan. Norco sold the exact same Sekai bicycles, with different stickers, throughout Canada, while Sekais were sold in the US.
Velocipede Bikes of Seattle
velobikeshop
Serial number verified model year. The model name is just a guess.
1983 Mountaineer
bikeforums
The fork is probably not original in this pic, as Sekai used biplanes through 1985.
1984 Sasquatch
bikeforums
Sekai used the following mountain bike model names from 1983 → 1990.
Norco used a similar, but not identical list of mountain models.
1985 Bigfoot
flickr
[1]. ?