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.
Bathed in every hot spring in the "Siege of Osaka (Summer)" chapter.
Equipped +15 divine equipment in all slots. (Excludes accessories.)
Made a total of 60 requests at the blacksmith.
Completed "The Grand Tournament" on Way of the Strong or higher.
Collected all the best materials.
Completed "The Master Ninja" on Way of the Strong or higher.
Completed "The Last Samurai."
Collected all Guardian Spirits.
Defeated all types of yokai.
Completed "Resentment Unleashed."
Defeated the Onmoraki during "Resentment Unleashed."
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)."
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.
Acquired mystic art for the kusarigama.
Acquired mystic art for the axe.
Acquired mystic art for the spear.
Acquired mystic art for the sword.
Completed "Yokai Country."
Acquired mystic art for the odachi.
Acquired mystic art for the tonfa.
Forged an item.
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.
Reached maximum proficiency with your first weapon.
Acquired mystic art for Onmyo Magic.
Completed "The Samurai from Sawayama."
Reached level 100.
Acquired mystic art for Ninjutsu.
Completed 10 missions with NPC or in the “Yokai Realm with a companion” with other users.
Completed "The Source of Evil."
Acquired mystic art for the dual swords.
Witnessed Tokugawa's forces head toward a decisive battle.
Met with Tokugawa Ieyasu.
Found Muramasa and brought him in.
Communicated with a yokai 10 times.
Completed "The Demon of Mount Hiei."
Defeated the Nue of Mount Hiei.
Changed your hair style or beard.
Collected all fragments of the Hiragumo teakettle from Shigisan.
Confused an enemy for the first time.
Completed "The Ocean Roars Again."
Lit all three evil-warding bonfires in Itsukushima.
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!
Used a disguise.
Changed the appearance of an item.
Bathed in every hot spring from the Kyushu Region to the Omi Region.
Collected all Kodama from the Kyushu Region to the Omi Region.
Became Ryunoshin the dung lover's best friend.
Used the mask of an ugly fellow to defeat an enemy.
Collected all Kodama in the Tohoku region.
Completed any mission while transformed into a woman.
Seized all of Aoba Castle's three-storied keeps in "The One-Eyed Dragon's Castle."
Listened to Katakura Shigenaga's entire introduction in "The One-Eyed Dragon's Castle."
Collected all Kodama in the "Siege of Osaka (Winter)" chapter.
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)."
Equipped the Kusanagi Tsurugi, Yasakani Magatama, and Yata Mirror.
Collected all Kodama in the "Siege of Osaka (Summer)" chapter.
Completed the 20th plane in The Abyss.
Destroyed all the destructible cannons in "The Sanada's Resolve."
Destroyed all the Revenant contraptions on "The Last Samurai."