How many titan shifters can harden their skin? I've just watched the anime series and in it, we've just seen the female titan and the armored titan being able to harden their skin. But reading in the internet I've found that


   In the manga Eren can harden his skin and so does the Beast Titan


is there any other titan shifters who can harden their skin? How many titan shifters can harden their skin?
This link explains all the abilities of every Titan :-

Titan Abilities

The titans that can Harden are :-


Beast Titan
Female Titan
Armoured Titan(dunno if you can call this hardening but he has hardened skin afterall!!).
Attack Titan