Here is the full list of all 79 Nioh: Complete Edition achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
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Completed the 20th plane in The Abyss.
Completed any mission while transformed into a woman.
Used a disguise.
Defeated Ganryu's Sasaki Kojiro using only Dual Wooden Swords. (Cannot use a Visitor/Companion.)
Bathed in every hot spring from the Kyushu Region to the Omi Region.
Listened to Katakura Shigenaga's entire introduction in "The One-Eyed Dragon's Castle."
Bathed in every hot spring in the "Siege of Osaka (Summer)" chapter.
Acquired mystic art for the tonfa.
Acquired mystic art for the dual swords.
Acquired mystic art for the axe.
Acquired mystic art for the kusarigama.
Equipped the Kusanagi Tsurugi, Yasakani Magatama, and Yata Mirror.
Defeated Sarutobi Sasuke in the mission "The Siege of Osaka (Winter)" using only tonfa. (Cannot use a Visitor/Companion.)
Used all the culverins in the mission "The Siege of Osaka (Winter)."
Equipped +15 divine equipment in all slots. (Excludes accessories.)
Collected all Kodama in the "Siege of Osaka (Summer)" chapter.
Destroyed all the destructible cannons in "The Sanada's Resolve."
Bathed in every hot spring in the "Siege of Osaka (Winter)" chapter.
Completed "The Grand Tournament" on Way of the Strong or higher.
Completed "The Master Ninja" on Way of the Strong or higher.
Collected all Kodama in the "Siege of Osaka (Winter)" chapter.
Seized all of Aoba Castle's three-storied keeps in "The One-Eyed Dragon's Castle."
Collected all Kodama in the Tohoku region.
Bathed in every hot spring in the Tohoku region.
Completed "The Last Samurai."
Collected all Guardian Spirits.
Defeated all types of yokai.
Destroyed all the Revenant contraptions on "The Last Samurai."
Completed "Resentment Unleashed."
Defeated the Onmoraki during "Resentment Unleashed."
Collected all Kodama from the Kyushu Region to the Omi Region.
Completed "The Sanada's Resolve."
Completed "The Sparrow Flies Again."
Completed "Scion of Virtue."
Defeated all of Sanada's Ten Braves in "Scion of Virtue."
Completed the mission "The Siege of Osaka (Winter)."
Collected all the best materials.
Completed "Hands of the Dragon."
Completed "Spirit Stone Huntress."
Completed "The One-Eyed Dragon's Castle."
Completed 10 missions with NPC or in the “Yokai Realm with a companion” with other users.
Defeated Derrick the Executioner.
Completed "Yokai Country."
Defeated the Nue of Mount Hiei.
Acquired mystic art for the odachi.
Acquired 40 gestures.
Made two circuits around Japan.
Completed "The Queen's Eyes."
Acquired mystic art for Ninjutsu.
Completed "The Demon King Revealed."
Obtained first divine item.
Acquired mystic art for the sword.
Acquired mystic art for Onmyo Magic.
Completed "The Samurai from Sawayama."
Acquired mystic art for the spear.
Completed "The Source of Evil."
Reached level 100.
Reached maximum proficiency with your first weapon.
Made a total of 60 requests at the blacksmith.
Witnessed Tokugawa's forces head toward a decisive battle.
Became Ryunoshin the dung lover's best friend.
Met with Tokugawa Ieyasu.
Found Muramasa and brought him in.
Communicated with a yokai 10 times.
Completed "The Demon of Mount Hiei."
Forged an item.
Collected all fragments of the Hiragumo teakettle from Shigisan.
Changed the appearance of an item.
Completed "The Ocean Roars Again."
Used the mask of an ugly fellow to defeat an enemy.
Lit all three evil-warding bonfires in Itsukushima.
Completed your first Twilight mission.
Changed your hair style or beard.
Confused an enemy for the first time.
Completed "Deep in the Shadows."
Bathed in first hot spring.
Reached level 10.
Completed "The Man with the Guardian Spirit".