Zynga CEO Mark Pincus back in October, Zynga Japan will be closing its doors as part of a company wide "Cost Reduction Plan" this January. The decision was made official by an announcement on Zynga Japan CEO Kenji Matsubara's Facebook profile, where he thanked users for playing his company's games.
Three of Zynga Japan's games have already been discontinued: City builder Machitsuku, Scrabble clone Mojitomo and monster training RPG Montopia. Zynga Japan's mobile card battling game Ayakashi (available in the US as Ayakashi: Ghost Guild) will continue to operate beyond the developer's official closure at the end of January, 2013.
Other branches affected by the Cost Reduction Plan include Zynga Austin, which suffered a significant reduction in staff, along with Zynga Boston, which was closed entirely.