This is stacy.

Stacy Hirano is the best friend of Candace Flynn and good friends with Jeremy and Jenny. She is usually heard talking to Candace on her cell phone. Sh is usually more relaxed Candace when it comes to Phineas and Ferbs antics.

While she is mature most of the time she often will freak out over something like Cadance if it's something exciting.

She has several Japanese relatives.