Full guide: https://steamcommunity.com/sharedfiles/filedetails/?id=2972481961
intro:
Sakuna's post-game consists primarily of Amagaeshi Shrine, which you unlock halfway through the main game. It's hard to find info online about rewards and their rarities; in game, each reward appears with a specific frequency, represented by a number of asterisks in the game file. The exact relationship between these asterisks and the drop rates is unknown.
Every fifth floor of Amagaeshi shrine features a boss; upon its death, a green glow appears and you receive a special reward. You can only complete up through floor 60 before completing the main story, but in the post-game you can go up to floor 300.
There are two types of rewards: Equippables (weapons, items, clothes, etc) can only be obtained if the item isn't already in your inventory. E.g. you cannot get two Soldier Hat+'s. But after you turn your first Soldier Hat+ into the Wheeling Hat+ at Yui, you can then obtain a new Soldier Hat+.
If you're looking for a particular reward item, after killing the boss you can reload your auto-save, to kill the boss again, and try for a different reward item.
