Possibly Takagi cranks, maybe KKT Lightning pedals. More good stuff. Very wide gearing freewheel that could be an "Ultra" six-speed Suntour if you're lucky. Red-ano UKAI or ARAYA hoop --if that's what the rear is -- is also dope with the BMX and cruiser crowd. Suntour thumbies, if it has 'em, are worth $25-50 on their own.

Prevalence of Japanese parts, and geometry including box-crown fork, indicates a Japan-made and early MTB. Not a Diamond Back or Miyata though.

If early '80s Japanese parts are your game, it's a no-brainer at $50.