It looks like an early Sekai "Bigfoot" I just bought. Sumo 26 x 1.75 rims, Tourney crankset (26-36-46), Victor bear trap pedals (imitation Suntour XC II pedals), Suntour Power Ratchet Thumb shifters, Suntour Perfect 5-speed (14-18-22-26-30), Suntour AG tech front/rear derailleurs, SR seatpost. Strangely it has a SR front hub with a Shimano rear hub. I bought mine off CL for $40! It also has one of those early MTB/BMX top load stems with 4 bolts. The handlebars are steel & 22.2 mm entire length. Rear dropout is 128 mm. FWIW it weighs 33 lbs. I cleaned, removed surface rust & clear coated raw steel, new brake pads, cables, housings, slapped on an old Brooks B76, new tires and grips. I also cleaned & re packed all bearings (headset, BB, hubs, freewheel & even the pedals). The one in the photois even a similar color - looks sea foam green in photos & certain light and looks metallic silver in direct sun. It's a fun ride. Likely my new favorite.
Good luck & do say what you find out.