I don't have any good suggestions, but are the croissants at these high-profile artisan bakeries significantly better than what you get at, say, Pompadour?

I went to a well-regarded French place in Roppongi but didn't think theirs was really special.
Lot of Japanese people think Maison Keyser is great, but I still think Pompadour's croissant is better.

There's a shop called Pain Traditionel (or something like that). Very good.

The best shio-pan award goes to Pain Traditional and Vie de France, for sure.