It's Kotone!

The female protagonist of Persona 3 Portable.

Unlike her Male Protag counterpart, she has a can-do, excitable, and even a bit of a flirty tone... but shares the same depression as Makoto underneath. For this role, you'll need to be able to show off both sides of Kotone in order to get the message across. 

As a quick note, due to the nature of Kotone's role, I'm gonna be doing a "Callback" system for casting Kotone. If I feel you're a good candidate, I'll contact you with some extra lines I want you to read. She'll be the only character I'm doing this with, since all of her responses are very short.