Teizokurei Monophobia

A high school girl named Houdzuki Maika shares her life with her deceased twin brother Maito, who exists within her and alternates living each day with her. They share most of their memories and can only communicate when both are asleep, experiencing the same dream. Maika can see ghosts, likely due to this unusual coexistence. In the first volume, a school counselor involves her in an investigation concerning a missing female student, whose ghost has left a message etched into a classmate. The twins are expected to encounter further mysterious events.