There's green writing earlier on which seems to be a party member/another player, so I'm guessing this might be an objective marker, unless there are also other players who aren't in your party.
That looks like it's at the other side of the lake, even if there were an out of party player all the way over there, it makes no sense to have his name so big (compared to the player size at such distance) if it has nothing to do with your party/mission. So it's probably just a mission/place marker.
As someone earlier said, if this has something to do with that Massive Single Player Online Game that Nintendo trademarked before, meaning as in although you'll meet other people, you only share the world-space and join them if you want to, for random quests, boss fights.
Genre: MSORPG - might as well be.