Considering it's not massively multiplayer (4 players together max like PSO), not strictly speaking online (online option, not manditory, again like PSO but without content locked away online), and could only tentatively be described as a Role Playing Game since there's really only one role (a Hunter of Monsters, or Monster Hunter) although you are free to choose how you wish to go about your singular task of dismantling all other life in the universe thanks to a variety of weapon classes. No, it is not an "mmorpg."
Really it's more like Boss Rush: The Game, with crafting / item gathering and a multiplayer option. --- Don't get hit and hit it until it dies, in that order. Kill it, carve it, wear it, repeat it.