Japanese permanent resident here.

Epidurals are very rare. They exist but they are not popular at all. Some is the belief that a “natural” birth is better. In some cases it is just availability of an anesthiaologist that is equipped to do one. Some people just don’t even realise it is an option. The only people I know here who have had one were non-Japanese residents.

I don’t think people necessarily look down on a mother who has one, it’s rare enough that nobody would even ask probably, but it’s just not a common procedure.