This guide may contain major spoilers of the game's story, it is recommended to play the game first for its full enjoyment.

PD: Sorry for my bad English, it's not my primary language.

2 ~ 4 Hours

No extra requirements needed, just play the game

The Beginning
Pressed the switch to open the first door


Apprentice Shrine Maiden
Defeated 15 enemies in one stage


First Job
Broke a seal to a gate between worlds for the first time


To Battle!
Opened 4 gates between worlds


The Forest of Awakening
Cleared The Forest of Awakening


The Sunken Relics
Cleared The Sunken Relics


The Scorching Labyrinth
Cleared The Scorching Labyrinth


The Ruins of Yamataikoku
Cleared The Ruins of Yamataikoku


Blade of Kusanagi
Cleared playing Yamato


Magatama of Yasakani
Cleared playing Uzume


Mirror of Yata
Cleared playing Hinome

Gather all the items and secrets hidden in every level

Brimming with Power
Have a playable character with max stats of HP12 and SP400


Items can be found through the levels (inside hidden chests) and at the end (before the boss fight). You must find every single chest, there are 8 in total (2 per level), plus the items in the room before the encounter (also, 2 per room)

Sushi in the Trees *
Find the hidden sushi in The Forest of Awakening


Burger in the Ruins *
Find the hidden burger in The Sunken Relics


Crow in the Labyrinth *
Find the hidden crow (?) in The Scorching Labyrinth

Yamataikoku Doll *
Find the hidden doll in The Ruins of Yamataikoku










The "Interaction" button will pop up.





* Getting these achievements will unlock:

Explorer
Found all secret items within the same save data


Songs to remember
Unlocked Sound mode


Note: Secrets only need to be collected once as any character to unlock the sound test.
Note 2: Secrets and upgrades are in the same location for every character.

** Please use this guide to know exactly where the items and secrets are
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2044576708
Also, thank you Taake for making that guide, it helped me a lot.

Time consuming, kinda

Demon slayer
Killed 3000 enemies in one save data


Destroyer
Destroyed 1500 objects in one save data


Note: It's no biggie, just follow the instructions in the description of the achievement. Just make sure to do it in the same save data.

To do while in-game, just to show skill or something

Fatal Blow
Unleashed all 3 of the playable characters' Special Attacks in one save data


Psss...hold and release that "attack" button with every character.

God of Combos
Chained 100 combos


This one can be easily be achieved during boss fights, where enemies just spawn endlessly (especially, during the Final-Final boss (?) fight, just camp on the side with Uzume during its 4th phase [that's the way how I achieved it, leave your way in the comments if you like].

Clearing the game under some requirements (involves speedrunning it)

All the way
Didn't use Continue to clear the game


Again, no biggie, just complete the game without using the "Continue/Retry" option.
Tip: If you die, just close the game, start it again and continue where you left off, it will not count as a "continue".

Blessed Shrine Maiden
Cleared game within 30mins


Enlightened
Cleared the game within 30mins for each of the 3 playable characters within the same save data

Don't worry, you don't have to be Frame-perfect to achieve sub-30 in this game. Just hold on that "run/dash" button all the time.

Maybe the hardest achievement in the game

Untouchable
Cleared the game with no damage


Tips:
1). BE PATIENT, don't rush or else you'll get hit easily.
2). Use your Special Attacks to escape (you're invincible during your Special attack).
3). If you get hit, just quit, return to the main menu, and then continue (Remember happy day, if you activate a Torii (Gate) the game will save, make sure to reach one without getting hit, so when you restart, you don't have to do it from the beggining.
4). Know the mapping, or else you'll get stuck in a dead end and get hit.

Recommendation:


She can attack every enemy from a safe distance, and her Special attack gives her too many invincibility-frames (aside from attacking every enemy on-screen, useful during boss fights).

Savior of the Transient World
Unlocked all Achievements


Congratulations, you unlocked everything!