Monster Hunter Frontier Z is a Monster Hunter-themed MMORPG that hasn't received an official release outside Japan, Korea, and China (yet). It debuted on the PC in 2007. It's since undergone some revisions in addition to eventually seeing release on the PlayStation 3, PS Vita, Wii U, and Xbox 360.
That console support base is about to get a bit smaller, however. Capcom recently announced it's dropping Xbox 360 and Wii U support for Frontier Z come August 1, 2018 (via Siliconera). Capcom admits since neither console is being manufactured anymore, providing technical support as necessary is rough.
Anyone who has a Monster Hunter Frontier Z account on one of the doomed consoles will have it moved to the PC.
Monster Hunter Frontier Z is the latest iteration of Monster Hunter Frontier. It's preceded by 2013's Monster Hunter Frontier G.