I did not know that there is still a Kinship Level to unlock :O! WTF? 😀 Need to get that done too! So in order to unlock Kinship 9 and 9 Star Missions is a Quest Line which starts in Mahana and goes through Lulucion. You have to hunt some Deviant Monster and then you get the last Kinship Level! A Full Walkthrough for the Unlock can be found here: https://www.casual-ben.com/blog/2022/02/12/how-to-get-kinship-level-9-and-9-star-quests-in-monster-hunter-stories-2/
In this article I will teach how to, well, I’m pretty sure the title gave it away already, but how to get kinship level nine, and start quests level nine. However, remember that this content can only be accessed after you finish the game. So if you’re still not done with the main story, finish it, and then come back to read this so that you can discover how to access this post-game content.