Pretty neat! The orange sticker is a local registration sticker, from Saitama-ken, in Kanto and basically part of the sprawling Tokyo metro area. So the bike definitely spent some time in its home market.

The Nitto bars are newer than the bike, I think, or it's also possible Nitto's been making the same bar forever. The bars certainly look newer/shinier/less-corroded than the other parts. The B115 is still in Nitto's catalog, still available everywhere. Not sure if they've updated the stampings, but I have 3 or 4 stamped the same bought some time in this century.

Don't think I've seen that Panny stem before. Kinda neat, looks like a Cinelli 1R knockoff from the front, but has a standard-ish bar clamping setup.

I googled a little bit, lotsa images out there of PC-700s, not a lot of data.