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.


Below, you'll see a list like the following: (Floor 175, 180):
Branching Flower x5 ***
Stainless Steel ***
Demonic Braid ***
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Another way of wording this is you have three rarity 3 rewards (Branching Flower x5, Stainless Steel, and Demonic Braid), and six rarity 10 rewards (each flake).

Each reward is weighted by 1 over its rarity. So doing the math, the total weights are 1/3 + 1/3 + 1/3 + 6/10 = 1.6 total weight. So you'll receive flakes 3/8ths of the time, any specific flake 1/16th of the time, stainless steel (1/3 / 16/10 = 10/48 =) 5/24ths of the time, demonic braid 5/24ths of the time, and branching flowerx5 5/24ths of the time... given that you already received all the non-renewable rewards.

A more complete view shows eight rarity 2 equippables and two rarity 1 equippables, so the true total weight is 1.6 + 8*0.5 + 2*1 = 7.6. In other words, if you don't have any of the ten possible equippable rewards, you'll receive a new one with 15/19ths chance!

First, the three unique boss drops (Black Dear Leather from Black Shadow, Pheasant Feather from White Gale, and Boar Tusk from Purple Scourge) do not drop from their boss equivalents in Amagaeshi shrine. If you want to farm more than 2 per day (one from day, one from night kill), you can do floors 55,60,155,160 to get possible more drops -- Black Dear Leather and Pheasant Feather can also be obtained from the final normal mission in the base game.

Secondly, good non-reward farming:

• Levels 16-20, 116-120, 216-220 all have plenty of Deer for Antlers -- you need them to awaken some gear
  
• Levels 21-30, 121-130, 221-230 are great for Aqueous Droplet farming at night, a great addition to your fertilizer.

Finally, reward farming:

• Flakes: Best obtained from floors 175 and 180, 100, 200, and 300. Each has a 3/8ths chance for flakes, with a 1/16 chance for a specific flake; other than floor 300, which has a 6/7ths chance for flakes and 1/7th for a specific flake, but the boss is significantly more difficult with significantly more HP.
  
• Crane Feather, Dragon Bone, Dragon Scale: Most likely from 255-295

Gear tips for farming enemies and raising your rice:

• 1-Handed: (whatever is strongest you have -- eventually Brand of the Ascendant+)
  
• 2-Handed: Gold Rake+ -- find it from floors 250-295
  
• Garment: Enamel Hunter's Garment+ -- find it from floors 105-150
  
• Hat: Conical Hat+ -- find it from floors 105-150
  
• Mask: Kamuhitsuki Mask -- find it from beating floor 74 of Sakuna the Effluescent (Aphid Extermination minigame)
  
• Spirit Boughs (6 slots) -- Tycoon, Luck Boost+, Huntress, One-Handed Power Boost, Two-Handed Power Boost, Headgear Power Boost

An alternative mask is Soul-Stealing Mask+ which makes enemies drop 1.3x more stuff... but it doubles incoming damage. An alternative 1-handed weapon is Gold Iron+, which buffs garments +20%. In both cases, you will lose so much time from dying, or failing to quickly kill enemies, that it's not worth the buff in enemy drop rates.


At night: Do floors 221-230 for Aqueous Droplets and possible Cloudy Crystals from bosses

During day: Do floors 171-180 for flakes (3/8th chance per boss), as well as a ton of amber. Then do floors 100 and 200 for cloudy crystals or flakes (flakes are also 3/8ths chance)

Cloudy Crystals give +25 to each rice attribute, so they're as good as Medicinal Bases for your rice. Flakes give +50, but Gusto Flakes give +200 stickiness in medicine. Never put Gusto Flakes in fertilizer!!

• Make sure you have all available animals. By endgame you should have 5 dogs, 5 cats, ducks, and a cow. Obtain new animals by sending Kaimaru to new gathering areas (all 11 of them) and then immediately returning home.
  
• Send Kaimaru to get you Remedies, then send all other 4 to the Caverns -- you should get 1-2 Medicinal Bases per day. Do not bother with powders -- a single powder is +20 in a single stat, vs Medicinal Base which is +25 in all.
  
• Make a gathering set too. Antler Thresher+, Tusk Pickaxe+, Enamel Hunter Garment+, Palm Hat+, Kamuhitsuki Mask. Use this when you're doing the "gathering" action as Sakuna.

Format: Item Name ****
Number of stars determines rarity: More stars, less common.

Powder of Transformation **
Moonlit Stone *
Clay x3 *
Copper Ore *
Oil Cake *

Powder of Transformation **
Metallic Sand *
Iron Ore *
Oil Cake x3 *

Powder of Transformation **
Aqueous Droplet *
Jade *
Ice *
Oil Cake x3 *

Powder of Transformation * (Not a typo -- more likely here)
Moonlit Stone *
Stone x10 *
Oil Cake x3 *

Powder of Transformation **
Flaming Core *
Obsidian *
Oil Cake x5 *

Powder of Transformation **
Metallic Sand *
Ashigumo Shuriken *
Black Dear Leather *
Pheasant Feather *
Boar Tusk *
Oil Cake x5 *

Powder of Transformation **
Flaming Core x5 *
Bear Hide *
Badger Leaf *
Stainless Steel *
Demonic Braid *
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Branching Flower x5 *
Stainless Steel *
Demonic Braid *
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Branching Flower x5 *
Metallic Sand x5 *
Flaming Core x5 *
Aqueous Droplet x5 *
Moonlit Stone x5 *
Demonic Braid *
Cloudy Crystal ***
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Cloudy Crystal *
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Moonlit Stone ***
Clay x5 ***
Copper Ore x3 ***

Metallic Sand ***
Iron Ore x3 ***

Aqueous Droplet ***
Jade ***
Ice ***

Moonlit Stone ***
Stone x10 ***

Flaming Core ***
Obsidian x3 ***

Boar Tusk *
Metallic Sand ***
Ashigumo Shuriken ***
Black Dear Leather ***
Pheasant Feather ***

Flaming Core x5 ***
Bear Hide ***
Badger Leaf ***
Stainless Steel ***
Demonic Braid ***
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Branching Flower x5 ***
Stainless Steel ***
Demonic Braid ***
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Branching Flower x5 ***
Metallic Sand x5 ***
Flaming Core x5 ***
Aqueous Droplet x5 ***
Moonlit Stone x5 ***
Demonic Braid ***
Cloudy Crystal ****
Health Flakes **********
Strength Flakes **********
Vitality Flakes **********
Magic Flakes **********
Luck Flakes **********
Gusto Flakes **********

Leaf of Creation x2 ***
Cloudy Crystal ***
Crane Feather *****
Dragon Bone *****
Dragon Scale *****

Leaf of Creation x2 ***
Cloudy Crystal ***
Crane Feather ***
Dragon Bone ***
Dragon Scale ***

Cloudy Crystal *
Health Flakes *
Strength Flakes *
Vitality Flakes *
Magic Flakes *
Luck Flakes *
Gusto Flakes *

These are not one-time-only. For example, if you use Antler Bean Thresher+ to make a Hinanaka Thesher+, then beating level 120 again will get you another Antler Bean Thresher+. You simply cannot have two of any equippable in your inventory at the same time.

First clear of the following floors give the following results (Also guaranteed rewards if not in your inventory).

10: Spirit Bough: Snow Goddess
20: Spirit Bough: Rain Goddess
30: Spirit Bough: Sun Goddess
40: Spirit Bough: Brilliant Virtue
50: Spirit Bough: Iron Wall
60: Spirit Bough: Celestial Maiden
70: Spirit Bough: Null Charm
80: Spirit Bough: One-Handed Power Boost
90: Spirit Bough: Two-Handed Power Boost

110: Hat: Woven Hat+
120: 1H: Antler Bean Thresher+
130: 2H: Jade Sledgehammer+
140: Hat: Palm Hat+
150: Garment: Wheel Hunter's Garment+
160: Garment: Autumnal Hunter's Garment+
170: 1H: Copper Sickle+
180: Garment: Scale Hunter's Garment+
190: Mask: Demon Mask+
200: 1H: Hanamori Nutcracker+

210: Garment: Folding Fan Kamiko+
220: 1H: Oaken Hammer+
230: 2H: Fish Hook+
240: 1H: Obsidian Executioner+
250: 2H: Bamboo Broom+
260: Hat: Soldier's Hat+
270: Hat: Treasured Traveling Hat+
280: Garment: Wave Hunter's Garment+
290: 1H: Holy Tree Hammer+
295: 2H: Holy Tree Spade+
300: 1H: Scythe of Hoshidama+

In your mind, add these rewards to the previous sections if you don't have them yet. E.g. Floor 100 has three items with *** rarity; you're more likely to get them than the flakes, and less likely than the Cloudy Crystal.

100: Garment: Autumnal Hunter's Garment ***
100: 1H: Scrap Iron Sickle ***
100: 2H: Scrap Iron Hoe ***

105-150: 1H: Granite Mallet+ **
105-150: 2H: Granite Sledgehammer+ **
105-150: 1H: Iron Sickle+ *
105-150: 2H: Iron Hoe+ *
105-150: 2H: Tusk Pickaxe+ **
105-150: 1H: Demonic Pearl Ladle+ **
105-150: 2H: Demonic Pearl Pail+ **
105-150: Garment: Bamboo Hunter's Garment+ **
105-150 Garment: Pine Hunter's Garment+ **
105-150: Garment: Enamel Hunter's Garment+ **
105-150: Garment: Butterfly Hunter's Garment+ **
105-150: Hat: Sedge Hat+ *
105-150: Hat: Conical Hat+ **
105-150: Mask: Kitsune Mask+ *
105-150: Mask: Whistling Mask+ *
105-150: Mask: Hoary Mask+ **

155-195: 2H: Copper Hoe+ **
155-195: 1H: Iron Sickle+ *
155-195: 2H: Iron Hoe+ *
155-195: 1H: Jade Mallet+ **
155-195: Garment: Black Deer Hakama+ **
155-195: Garment: Destabilizing Kosode+ **
155-195: Garment: Thunderous Hunter's Garment **
155-195: Hat: Classy Hat+ **
155-195: Mask: Crow Mask+ **
155-195: Mask: Lucky Mask+ **

200: 1H: Scrap Iron Sickle+ **
200: 2H: Scrap Iron Hoe+ **

205-250: 2H: Steel Sledgehammer+ **
205-250: 2H: Oaken Spade+ **
205-250: 1H: First-Rate Sickle+ **
205-250: 2H: First-Rate Hoe+ **
205-250: 1H: Paper Fan+ **
205-250: Garment: Lunar Hunter's Garment+ **
205-250: Mask: Girlish Mask+ **
205-250: Mask: Soul-Stealing Mask+ **

255-295: 1H: Steel Mallet+ **
255-295: 2H: Obsidian Winnow+ **
255-295: 1H: Gold Iron+ **
255-295: 2H: Gold Rake+ **
255-295: Garment: Rice Hunter's Garment+ **
255-295: Garment: Wheel Hunter's Garment+ **
255-295: Garment: Woven Hunter's Garment+ **
255-295: Garment: Dragon Hunter's Garment+ *****
255-295: Mask: Tengu Mask+ **

300: 2H: Hoe of Hoshidama+ *****
300: Mask: Kamuhitsuki Mask+ **********


Note: The Kamuhitsuki Mask+ competes against seven one-star rarity items (cloudy crystal + 6 flakes), and one 5-star rarity item. So you have at most a 1/71 chance of receiving it upon beating this boss. Good luck.

All data was obtained from the game files themselves.

To check my work: Unzip "Sakuna of Rice and Ruin/dataWin/Common.arc", then in "Common/Param/Game/Amagaeshi" you'll find many files "Reward005.csvrw" for example. Open them with a hex editor and you'll see Japanese names.

In "Common/Param/Item" you'll find many files like "Enchant.csv" which contains Spirit Boughs, "Armor.csv" which is all garments hats and masks, and "Weapon.csv" with all 1H and 2H weapons. You can use these to translate the item codes into the English names.

Example usage for guide creation:

• Listing all rewards by exact location: "Common/Param/Bg/Ka/Main_1A/GetItem.json" shows that this area (the Main_1A area of the Fire region) contains the Stab Resist spirit bough.
  
• Updating the wiki with exact attack and defense values for all enemies. "Common/Param/Skill/Attack.csv" lists the damage types and damage multipliers of each skill
  
• Listing the upgrade costs and levels for each Spirit Bough and Weapon and Armor
  
• To be continued...