Thread:FrenchTouch/@comment-9803708-20161108075620/@comment-6548012-20161110131320

I don't know either, I've never had many sources on the matter, I think it's more related to something like the “former reigning year” or “original rule,” from the Genji era, so I find it weird that such a popular name doesn't that clear an etymology at all. Sorry for not being able to help. If you want my advice though, all of these sources look fishy.