Persona: Trinity Soul, Devil Survivor 2 The Animation Recommendations
Their both adaptations of the Persona JRPG series, both have a dark feeling to them. If you liked Devil Survivor be sure to give Trinity a try. Trinity has more suspense as well as character development.
-Trinity is a sequel to the Persona 3 series, slightly more realistic as well.
-Devil Survivor 2, is based off the Devil Survivor series (obviously) which Jackfrost is iconic in.
-Trinity's persona's take a spectral form, while in Devil Survivor, they come digitally and take physical form.