A Cruel Angel's Thesis (Zankoku na Tenshi no These) is the theme song of the popular anime Neon Genesis Evangelion. It is used as the opening to the series, and two instrumental versions of it are played in the finale episode, "Take care of yourself." These are "The Heady Feeling of Freedom" and "Good, or Don't Be", scored for violin, piano, and guitar. "The Heady Feeling of Freedom" is a somber and reflective piece for bowed strings and guitar, while "Good, or Don't Be" is played to a light piano and guitar tone. Both are considerably different in feel from the more hard driving techno-dance original.
And A Cruel Angel's Thesis was performed by Yoko Takahashi who is a Japanese singer from Tokyo.