The number of special achievements in "Assassin's Creed: Shadow" is very large, and the Ninja Achievement is one of them. Its requirement is to be proficient in the Ninja Way and buy each skill in Naoe's Ninja Skill Tree. You only need the first level of each skill, not every upgrade.
How to do Assassin's Creed Narcissus Technique Achievement
Purchase each skill in Naoe's Ninja Skill Tree. You only need the first level of each skill, not every upgrade. This requires a level 6 knowledge level, and you can increase the knowledge level by making orange activity icons on the map. In addition, 2 ninja skills need to complete specific side quests to unlock. They will show "Move Further in the Story" in the Skills menu, but they come from side quests.
Sweep Leg Skills - Complete optional quest "Fallen Soldiers" > "Genzaburo Soldiers" The first quest "Fallen Soldiers" will be automatically unlocked later in the story. This is a level 41 mission. It will appear under Harima's target menu and can be tracked from there. It leads to a waypoint in Harima, which gives us clues about the first Sword of Saburo. Killing the first will give the second a prompt. (This mission also unlocks the "Defense Breakthrough" skill for Yasuke)
Master the key insights - complete the side mission "Monster", which starts in the mountain city area.
