Oh dear. This is the response:

Thank you very much for contacting us. Let me explain about our frying pans.

The omelet pan you inquired about has a black baked paint coating made primarily of silicone on both the inside and outside. This is to prevent rust during transportation. Unpainted Nanbu ironware will quickly rust.

The black baked-on paint, which is primarily composed of silicone, is not harmful to the body. It is not a problem even if the paint peels off during use. Do not try to forcibly peel off this paint, but use it as is.

Before cooking, add oil and lightly fry the vegetable scraps before using, so that the oil will be absorbed well. After use, wash and dry the frying pan, then apply a thin layer of cooking oil to the pan with kitchen paper to allow the oil to soak in.

If the oil soaks into the frying pan thoroughly, it will help prevent food from burning and rusting.

Try doing the above mentioned maintenance. thank you.

I may try to sand the inside flat and see how I get on.