The Monster Hunter series has kind of fallen into a pattern. A new game in the series is released and it will contain two tiers of difficulty, low rank and high rank. Then, sometime after the release of said game, another game is released with a third tier of difficulty, such as Monster Hunter Tri and Monster Hunter 3 Ultimate. It is to be expected then that Monster Hunter Rise only contains the first two tiers of difficulty. That being said though, the way to unlock high rank in Monster Hunter Rise is a little bit different this time around.
While Monster Hunter: World changed the structure of the series by removing the separation of single-player and multiplayer quests, Monster Hunter Rise restores it. Veterans of the series may be tempted to power through the single-player quests in order to get to the high-rank version of single-player quests faster so as to get high-rank gear to take into multiplayer quests, but that tactic will not work this time.
To be clear, there are no high-rank single-player quests this time around. High rank is exclusively for the multiplayer hub quests and those quests are officially considered to be high rank at star level 4. There are two ways to get to this rank. The first is perhaps the most obvious, which is to simply go through the hub quests starting at level 1. They will operate the same as the village quests in which players will need to tackle a certain amount of key quests before being allowed to take a mission to go to the next star rank.
However, there is a second option which, for story purposes, is recommended. As players make their way through the village quests, they will be presented with special quests that are tests of sorts. Completing them will allow them to rank up in the hub quests without actually having to do the hub quests. There are three of these quests and unlocking them all will require players to reach the 6-star rank village quests.
If players have made it all the way to the 6-star quests in the village, then these special quests shouldn't prove too difficult. They are, however, different and more difficult in the sense that the game will ask you to hunt more than one monster in these quests. The second and third special quest both require three monsters to be hunted. Once these three quests have been completed or players have gotten to the 4-star hub quests the old-fashioned way, high rank will officially be unlocked. Getting to high rank this way will still award players with the appropriate hunter rank.
As of yet, there are no announced plans for the third rank of difficulty, often referred to as G rank quests, (though Iceborne changed the name to master rank). However, with the updates that Capcom is planning for Monster Hunter Rise, the third tier eventually coming is not out of the question.
Monster Hunter Rise is now available for the Nintendo Switch. A PC release is slated for 2022.