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