As preparation for her role, Nakatani watched the apology press conference held by Samurakochi Mamoru who had been found to use the music compositions of another person as his and came to the conclusion that although he seemed to be justifying his wrong actions, there was probably a side of him who really loved music. As such, Nakatani wants to project that side of her character who loves literature despite hiring someone to write under her name, In addition, as Nakatani herself is also a writer and has a regular essay column, she commented that she can understand the toughness of having writers' block as she would sometimes submit her work only when the deadline for her essay submission is almost due when she doesn't know what she should write.
With regard to the scene at the beginning of episode 1 where Nakatani and Mizukawa were fighting each other in the freezing rain where the temperature was below 5 degrees, there were actually stand-ins prepared for them but both actresses decided to do the scene themselves for reality's sake. However, as they got too serious about fighting each other in the rain, the tough experience was enough to make Mizukawa comment that she wouldn't want to do such a scene again because it was too cold and painful. Nonetheless, both of them were very pleased with the result and glad that they decided to do it themselves.
Source: Sanspo 1 / Sponichi / Sanspo 2