Source: Capcom
Best answer: No, you don't have to. Monster Hunter Stories 2 is a brand new story, separate from the original game. However, there are a few references to the first game that might go over your head.
A new Monster Hunter story!
Monster Hunter Stories 2: Wings of Ruin is the next installment in the Monster Hunter Stories series and a sequel that no one really expected. Monster Hunter Stories released on the 3DS in 2016. However, Monster Hunter was a still fairly niche series, and the 3DS already had one leg in the grave, with the Nintendo Switch set to release just a few months after. However, those who played it found an engaging RPG with a wealth of side quests and challenging turn-based combat.