This is Trina from Grojband, she is more evil version of Candance from Phineas & Ferb. Candance wants to get her brothers into trouble for the dangerous ventures. Trina wants to destroy her brother and his band and their dreams. Heaven help them when Trina is old enough to purchase firearms and she treats her friend Mina as a slave. She has a major quirk when she reaches an emotional high, usually anger but happiness, sadness, or fear has sent, she manically writes in her diary and these writings become the basis for Grojband's songs.

Katrina (Trina) Riffin is the 16 year old older sister of Corey, and serves as the main antagonist of the show. She is obsessed with destroying Grojband, and hates it with a burning passion. She appears to have severe anger-management issues, which Grojband uses to write good lyrics for the song they perform at the end of the vast majority of the episodes. They enrage her big time and she writes about it in her diary. They get it from her and put her words into lyrics. She is voiced by Alyson Court.

Trina is a cruel, stuck up 16 year old girl with anger issues. She holds a deep hatred toward her brother Corey and his band and often tries to goes out of her way to destroy them. She thinks that his band is annoying and nothing more than a waste of garage space that she could be using as her own private bedroom. Outside of her relationship with Grojband, Trina has no friends except for her best friend Mina who she acts very abusive toward. Trina treats Mina like a slave which is mostly out of her anger issues. Trina also has a secret crush on a boy named Nick Mallory. She always tries to make him fall in love with her but she is always failing at this. Mostly related to Corey and the band ruining this for her. Whenever Trina gets angered enough, she takes out her anger by writing in her diary whereas she jets up into the air on a geyser of flames and lava and writes in her diary which causes flames to come out of her pen. This is called Diary Mode. Trina is unaware of the fact that she does this as she forgets it every time she exits diary mode. She is also unaware of the fact that Corey is always stealing her diary and using her diary entries for lyrics, even though he insists that he uses them for inspirational purposes only.