Japanese serving bowl

This handmade bowl is 6.5" in diameter x 3.5" high, labeled Nakagama Japan and stamped with a kiln or artist mark. This is a very understated, but high quality bowl. I do not recognize the stamp. The glaze is amazing but only images 3 and 4 suggest that. I will try to get better images of the exterior of the bowl when I have some natural light to work with. Possibly a donburi bowl (donburi-bachi).

https://livejapan.com/en/in-tokyo/in-pref-tokyo/in-tokyo_train_station/article-a0005066/

I believe that Nakagama is/was a Japanese pottery exporter. Not sure if they are still in business. I am also not sure which American importer(s) used them. I suspect that they exported pottery to other countries besides the U.S., just a feeling. There is a Nakagama store in Canada so I called them and was told that they had seen pottery marked like this, but the name is a coincidence. They know nothing at all about this company. I have seen a few pieces with the mark on the Nakagama label stamped or painted in the glaze. A Mystery.

A seller on an on line auction site has had this bowl on offer for a couple of years, at a price I was unwilling to pay. I made a couple of offers, which were declined. Last week that price was greatly reduced so I could not resist.

Guessing it is a serving bowl as it is a bit large, I think, for a tea bowl. Probably less than 30 years old.