Becca

She is the spirit of a teenage girl that died in a train accident and at the beginning of the manga she is Kieli's roommate at Easterbury. As they encounter Harvey he confronts her about being a spirit and is extremely unnerved by her charade at pretending to be still alive. Deeply hurt Becca decides to get revenge by playing a "joke" on him. She wants to proof that he is an Undying by trying to kill him. She also tries to talk Kieli into helping her. As Kieli refuses Becca temporarily takes over her body to accomplish her goal thus putting Kieli in great danger and seriously hurting Harvey. Afterwards she regrets what she did and makes up with Kieli, who decides to follow Harvey on his journey towards the Corporal's grave. Seeing Kieli this happy and enjoying herself in Harvey's company Becca is finally able to find peace. She vanishes from the train they're riding together and moves on.