When to comes to spreading this game - or even gathering up players – the best opportunity: Anime Conventions.  If you happen to play this game and not watch anime, more power to you.  However, realize that anime conventions attract people who watch anime – which is connected to Japan.  Therefore, it's an environment where many people (not all) like things Japanese.  Chances are, you may find additional players of the game within the local area.

I note this especially when mahjong is getting some more attention as a mahjong related series is currently airing.  Not surprising, this is true.  So, this year is actually a good opportunity to do some "outreach".  If you happen to know this game, go ahead and setup a panel presentation on this game at an anime convention.  If possible, even rig up a block of time via Table Top Gaming for a room dedicated to mahjong.

Then see some results, maybe.  Anyways, just a suggestion.