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