Here is the full list of all 55 Onimusha: Warlords achievements.
Complete the game and get an S Rank.
Unlock Kaede's alternate outfit.
Complete the game on Ultimate difficulty.
Complete all stages of Oni Spirits.
Complete the game on Normal without enhancing swords or using Jewels.
Win a power struggle with a demon.
Complete the game in less than 3 hours.
Complete the game on Normal without using herbs or medicine.
Obtain the Bishamon Sword.
Strike Marcellus's final form with a Deflect Critical attack.
Collect all Fluorite.
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Defeat a demon by knocking it down the waterfall.
Cut down bamboo in the bamboo forest.
Strike a demon with Kaede's Special Attack.
Find the beetle on the tree trunk.
Spot the flock of wild geese at dusk.
Absorb souls from carp.
Collect all maps.
Kill a demon with a battering ram.
Solve all decoder boxes.
Collect all files.
Unlock Samanosuke's alternate outfit.
Defeat Fortinbras.
Defeat Marcellus's final form.
Open the gate to the Demon World.
Defeat Hecuba.
Solve all number puzzles.
Enhance the gauntlet to maximum.
Obtain all armor for Samanosuke.
Use Power Jewels to increase Vitality to maximum.
Use the Decorated Sword to enter the East Area.
Obtain all long-range weapons.
Enhance all orbs to maximum.
Defeat Barabazuu.
Obtain the Vision Staff.
Enhance all swords to maximum.
Complete the second half of the Dark Realm.
Defeat Stylado.
Complete the first half of the Dark Realm.
Obtain the Sacred Knife.
Speak to the first and second old moth man.
Obtain the Rosary of Communication.
Unseal the path to the Keep Underground.
Obtain the Arashi.
Defeat Marcellus.
Solve the crest puzzle.
Enhance equipment at Magic Mirror.
Enter the abandoned keep.
Obtain the Kouen.
Defeat Osric.
Save a soldier under attack by demons.
Obtain the Shiden.
Use a Special Attack to kill a demon.
Use the gauntlet to absorb demon souls.