Nicole is described as a bright, optimistic, mischievous, and cheeky girl. She is the 2nd most important character in the game and the support that Mark so desperately needs.

Even though she may put out a cheerful appearance under that mask she hides a persisting grief for the loss of her childhood friend Jake. She’s an individual who gives it her all, regardless of what challenge might come her way, and it shows. Mark and Nicoles relationship didn’t start out as friendly, but over time the two grow a genuine connection with one another. (btw she also likes to play the piano)

Example:

Yukino Yukinoshita from My Teen Romantic Comedy SNAFU