Beatrice is actually a split personality of Sayo "Yasu" Yasuda, who is also Shannon and Kanon. Shannon fell in love with Battler when they were little and they discussed about mystery novels when he visited Rokkenjima. One day, Battler made a careless promise to come back to take Shannon away in a white horse. Shannon took it seriously and suffered a severe heartbreak when he never returned and then forgot to write a letter for Shannon. Shannon then gave her love for Battler to Beatrice, a metaphor for Sayo trying to forget about Battler and move on, but those feelings never completely disappear.