HA! it's all so clear now: Panasonic=National=Matsu****a=...."S", naturally!
Great sleuthing again MauriceMoss, and BTW there's a Schwinn connection, too since Panasonic built some of the Japanese Schwinns under contract. But those would not have been labelled as Panasonics!
Looks to be Tange Champion "Motocross" tubing (whaaaa?) and came in at 24lbs. fully dressed in 1982 or 83:
1983 Panasonic DX-4000 Bicycle | Panasonic Bicycles Virtual Museum

HAH, the censors won't allow the proper JAPANESE name for Panasonic/National to be written since it contains a combination of letters than can only mean ONE THING to tiny dirty-minded computers...AFAIK this is the family name of the company's founder and actually means "beneath the pine tree"...obviously pornographic!