Sister Maria is among the faculty at St. Lucia Academy.
She first encounters Shion Sonozaki in the student guidance room, reprimanding her for habitual tardiness and disregard for other school rules. Sister Maria advises Shion to adapt to life at St. Lucia and follow the rules. She then discloses her role as the school's liaison officer. As Shion prepares to leave, Sister Maria inquires about Mizuho, mentioning that the incident in the school's pool is not the first for her.
The next time Sister Maria appears, she is with Ooishi and another detective investigating a girl's death. Sister Maria believes it to be a suicide and urges the detectives to conclude the case swiftly to protect the reputation of St. Lucia Academy. Upon Mizuho's arrival, Sister Maria shares details about an incident in her family with the detectives.






