This is the first anime which I binge watched and believe me I couldn't sleep at night thinking about it. This anime gave a great suspense and unexplainable feeling. The characters were amazing(especially Ray and Norman). The story of Isabella actually made me cry. Also the character which was just introduced after season 1 "Leslie" was a quite great. The character development of Sister Krone was amazing.
Overall, I want to say that I have watched many anime series but this one holds a special place in my heart.