User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-4841654-20130218003619/@comment-4813670-20130218125105

That's pretty much it, you're right BellGoRiiing. More precisions: to rank up, you need to do urgent quests, that's all. No points, nothing. Do the key quests and other urgents so that you reach the final urgent (that is, beating the guran miraosu to reach rank 8). THEN, and only then, and because all the quests you have been doing so far actually earned you points, it's gonna unlock many ranks at once.

For example, to make it clearer, once I beat the guran miraosu, I jumped from rank 8 to 55 or so at the end of the urgent, because all the points that accumulated through the quests I had done from HR1 up to the urgent valued as much points as those to reach rank 55.

This only prevails for the harbor quests.