This is Istoriya, a guardian spirit who used to live in a lost tomb. She was supposed to guard a lost collection of ancient knowledge, until Malvano stumbled upon her in his quest for knowledge for his library. Rather than guard the books there, he promised them safekeeping in his library. Now, Istoriya protects the entire library alongside Malvano, keeping watch over everything.

Art by: https://ych.commishes.com/user/Pinkish_Clown/