Full list of all 51 Aragami achievements. It takes around 15-20 hours to unlock all of the achievements in the base game on Windows.
The base game contains 39 achievements, and there is 1 DLC pack containing 12 achievements.
Obtain all 'Oni' medals
Get killed by an arrow while throwing a 'Kunai'
Perform an aerial kill from a 10m height
Perform a Ceiling Kill
Use an explosive light to kill a guard
Complete Chapter 13
Obtain all 'Yurei' medals
Obtain all 'Kami' medals
Find all Scrolls
Complete Chapter 12
Complete Chapter 11
Complete Chapter 10
Complete Chapter 9
Complete Chapter 8
Complete Chapter 7
Complete Chapter 6
Obtain a 'Kami' medal
Perform a Ledge Kill
Use 'Shinen' to swallow 3 guards at the same time
Perform your first Shadow Kill
Unlock all Skills
Die. Again. And again.
Completer Chapter 5
Complete Chapter 4
Kill 100 enemies
Destroy a Light Orb
Complete Chapter 3
Make a guard suspicious 3 times in a row
Die while performing a stealth kill
Complete Chapter 2
Summon 100 shadows
Perform 100 Shadow Leaps
Unlock a Skill
Find a Scroll
Complete Chapter 1
Obtain a ‘Yurei’ medal
Obtain a 'Oni' medal
Concatenate multiple stealth kills
Skip a cinematic
Complete Nightfall: Chapter I
Complete Nightfall: Chapter II
Complete Nightfall: Chapter III
Complete Nightfall: Chapter IV
Recover all Nisshoku Daggers
Kill two enemies at once with the help of Twin Shadow (Single Player)
Kill 4 or more enemies at once with the Explosive Kunai
Obtain all 'Kami' medals in 'Nightfall'
Obtain all 'Oni' medals in 'Nightfall'
Obtain all 'Yurei' medals in 'Nightfall'
Blind 4 or more enemies with a Shadow Grenade