Mejiro is a popular writer of yaoi manga. Due to her social anxiety disorder she keeps herself barricaded in her room, and has only been seen a few selected times by Chieko. Her only communication with the Amars are sheets of paper slipped under her door. Sometimes she has the Amars help her out with her manga, especially near deadlines. She has a strong dislike of men.
Though a recluse, Mejiro seems to be particularly self-centered. She manages to get the other Amars to cater to her, and states that she is the person most affected by the possible loss of Amamizukan.