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.
Defeated Ganryu's Sasaki Kojiro using only Dual Wooden Swords. (Cannot use a Visitor/Companion.)
Acquired mystic art for the dual swords.
Acquired mystic art for the axe.
Used the mask of an ugly fellow to defeat an enemy.
Completed any mission while transformed into a woman.
Completed "The Last Samurai."
Collected all Guardian Spirits.
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 10 missions with NPC or in the “Yokai Realm with a companion” with other users.
Completed "Resentment Unleashed."
Completed "The Sanada's Resolve."
Completed "The Sparrow Flies Again."
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)."
Communicated with a yokai 10 times.
Completed "Hands of the Dragon."
Completed "Spirit Stone Huntress."
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."
Completed "Yokai Country."
Acquired mystic art for the kusarigama.
Acquired 40 gestures.
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.
Acquired mystic art for Onmyo Magic.
Acquired mystic art for Ninjutsu.
Completed "The Samurai from Sawayama."
Acquired mystic art for the sword.
Used a disguise.
Completed "The Source of Evil."
Reached level 100.
Acquired mystic art for the odachi.
Witnessed Tokugawa's forces head toward a decisive battle.
Became Ryunoshin the dung lover's best friend.
Met with Tokugawa Ieyasu.
Made a total of 60 requests at the blacksmith.
Found Muramasa and brought him in.
Completed "The Demon of Mount Hiei."
Defeated the Nue of Mount Hiei.
Reached maximum proficiency with your first weapon.
Collected all fragments of the Hiragumo teakettle from Shigisan.
Completed "The Ocean Roars Again."
Changed your hair style or beard.
Lit all three evil-warding bonfires in Itsukushima.
Confused an enemy for the first time.
Completed "Deep in the Shadows."
Completed your first Twilight mission.
Forged an item.
Bathed in first hot spring.
Changed the appearance of an item.
Reached level 10.
Completed "The Man with the Guardian Spirit".
You have unlocked all achievements!
Acquired mystic art for the spear.
Collected all the best materials.
Bathed in every hot spring from the Kyushu Region to the Omi Region.
Equipped +15 divine equipment in all slots. (Excludes accessories.)
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.)
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.
Destroyed all the destructible cannons in "The Sanada's Resolve."
Defeated the Onmoraki during "Resentment Unleashed."