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.
Completed the mission "The Siege of Osaka (Winter)."
Completed "Hands of the Dragon."
Completed "Spirit Stone Huntress."
Completed "The One-Eyed Dragon's Castle."
Seized all of Aoba Castle's three-storied keeps in "The One-Eyed Dragon's Castle."
Found Muramasa and brought him in.
Acquired mystic art for the sword.
Completed "Yokai Country."
Defeated all types of yokai.
Completed "The Last Samurai."
Destroyed all the Revenant contraptions on "The Last Samurai."
Completed "Resentment Unleashed."
Defeated the Onmoraki during "Resentment Unleashed."
Completed "The Sanada's Resolve."
Changed your hair style or beard.
Lit all three evil-warding bonfires in Itsukushima.
Reached maximum proficiency with your first weapon.
Reached level 100.
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."
Completed "The Source of Evil."
Witnessed Tokugawa's forces head toward a decisive battle.
Changed the appearance of an item.
Met with Tokugawa Ieyasu.
Completed "The Demon of Mount Hiei."
Defeated the Nue of Mount Hiei.
Used the mask of an ugly fellow to defeat an enemy.
Completed "The Ocean Roars Again."
Confused an enemy for the first time.
Forged an item.
Completed your first Twilight mission.
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 axe.
Acquired mystic art for the kusarigama.
Acquired mystic art for Ninjutsu.
Acquired mystic art for Onmyo Magic.
Used a disguise.
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.
Communicated with a yokai 10 times.
Bathed in every hot spring from the Kyushu Region to the Omi Region.
Acquired 40 gestures.
Collected all Kodama from the Kyushu Region to the Omi Region.
Collected all Guardian Spirits.
Became Ryunoshin the dung lover's best friend.
Collected all fragments of the Hiragumo teakettle from Shigisan.
Collected all Kodama in the Tohoku region.
Acquired mystic art for the odachi.
Equipped +15 divine equipment in all slots. (Excludes accessories.)
Bathed in every hot spring in the Tohoku region.
Completed any mission while transformed into a woman.
Listened to Katakura Shigenaga's entire introduction in "The One-Eyed Dragon's Castle."
Completed "Scion of Virtue."
Collected all Kodama in the "Siege of Osaka (Winter)" chapter.
Acquired mystic art for the tonfa.
Bathed in every hot spring in the "Siege of Osaka (Winter)" chapter.
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.)
Used all the culverins in the mission "The Siege of Osaka (Winter)."
Defeated all of Sanada's Ten Braves in "Scion of Virtue."
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.
Collected all Kodama 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.
Destroyed all the destructible cannons in "The Sanada's Resolve."