Erina Nakazaki will play Kiriko Nakazaki who had found an Alter Book which helped her in her success. This Alter Book powered Ari Megid which is also voiced by her. Along with playing both the role, the she is also performs Ending Song "Determination" which is written and composed by her.
In the post credit scene, a person picks up another Alter Book which is related to Kirigirisu Megid and this will connect to Episode 2.
When it comes to the production of the episode on the whole, it is filmed completely with Blue Background and it gives a Stage Show like feel. Most probably the scenes were filmed without cuts.