I thought about it all afternoon, but I didn't have a word.

It's not about Carvin, it's about thinking about the emotional line that should be advanced.

Yoo-ri, Yoon-a or Taeyeon.

This is also a spoiler, anyway, it is clear in the introduction that Yuna and Taeyeon must be the heroines.

It's a change today, and the plot is being carefully considered.