Can I perform a backstab? If so, how?

All you need to do is purchase a skill from NINJA TREE, sneak up to an enemy and press TRIANGLE, you either do an animation like in the video above, or, when it's a different opponent e.g. a YOKAI, you jump on his back and do a downward slash, pretty slick

How To Unlock Ninja Tree :

Once you clear the Isle of Demons quest (1st Japan Mission) you will unlock the Dojo Mission at your starting point called 'The Way of the Ninja: Novice'

Complete this mission. Once you have finished this mission all you need to do is go into your Learn Skill menu, move across to Ninja then scroll nearly all the way down the bottom. The skill sticking out on the left is called Sneak attack. Purchase it for one point and you now have the backstab/ sneak attack!

How To Get Ninja Skill Points :

Unlike the Samurai skill points in Nioh, you won’t simply acquire more Ninja skill points just by using your Ninjutsu skills.

Skill points can be obtained by using Locks of Hair. These can be found all throughout the world of Nioh, and sometimes they might even be offered as rewards for completing a main mission or sub-mission. All you have to do is access your inventory and use the item to get the points. After that, you can spend the points in your skill tree menu.

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