My first mountain bike was a Nishiki Barbarian, probably a 83 or 84 - not the elevated chain stay one.
It was replaced by a new 86 Cannondale - which was retired with a cracked seat tube.
Nishiki Barbarians are extremely rare with no documentation - I only see 3 bikes in Google and no details. Even weirder, one of the Barbarians in Google has a lugged frame and one is TIG welded.

The Nishiki Bushwacker seems to be an identical bike so when I saw one in the largest size on the local buy and sell site for $20 I couldn't resist. It was dirty, greasy and rusty, worn out drivetrain, no front derailleur or shifter and a junk crank.

A new freewheel and a spare chain from an old upgrade, the Sugino crank and Suntour Power Ratchet shifters from my Cannondale fixed up the drivetrain. The Nishiki still had the Suntour Mountain Tech 3 pivot rear derailleur but when I went to clean it up I found it had no upper pulley - the chain was running metal to metal. I only had an early XT rear derailleur so used that. Front derailleur came from my junk box. Just found a Suntour XC Sport 7000 rear derailleur at the co-op so replaced the XT.

The bike came with a SR slingshot style stem but to me vintage MTB's have bullmoose handlebars. Found the bar in the local co-op in the bottom a a big box for $5. Few other pieces here and there, Velo Orange cables and it's getting close. Needs a bit more cleaning, new tires. Should put vintage style grips on it but like lock-on's too much.

Replaced the rusty pitted headset with a Velo Orange JIS headset today. Looked at a Neco headset that was actually a better match for the old headset and much cheaper but it was just so cheap - races weren't polished at all. The Velo Orange was so nice looking.
Trying to decide what to do to help hide the rusty chain stay.

Wonderful machine!