She is the spirit of a teenage girl who died in a train accident and at the start of the manga, she is Kieli's roommate at Easterbury.
When they meet Harvey, he confronts her about being a spirit and is deeply disturbed by her pretense of still being alive. Deeply hurt, Becca decides to seek revenge by playing a "joke" on him. She wants to prove that he is an Undying by trying to kill him. She also tries to persuade Kieli to help her. When Kieli refuses, Becca temporarily takes over her body to achieve her goal, putting Kieli in great danger and seriously hurting Harvey.
Afterwards, she regrets her actions and reconciles with Kieli, who decides to follow Harvey on his journey to the Corporal's grave. Seeing Kieli so happy and enjoying herself in Harvey's company, Becca finally finds peace. She vanishes from the train they are riding together and moves on.
