Macron?

I'm doing OCR on an 1890s Judo article which mentions several Japanese names. Some of them have small o's and u's with a macron accent ( ¯ ) above them. Does anyone know how to produce these characters in HTML? Damned if I can figure it out, and the closest I've been able to find on any site that lists these characters is a macron on its own ¯ and ò which isn't right.

I could probably find these in a character set and paste them in, and hope that it's the same in all character sets, but if possible I'd like to do it properly.