Mikaru Amagi is introduced in the second season of the series as a wealthy but profoundly lonely girl who is set apart from other children by her Panthalassan blood. She first appears when she finds Kaito Domoto on a beach after he loses his memory in a surfing accident, and she quickly becomes infatuated with him. Her personality is defined by a deep sense of isolation and a desperate longing for affection, which leads her to cling to Kaito and try to keep him close, even to the point of resorting to manipulative behavior such as feigning illness to prevent him from seeing Lucia. Her primary motivation is the need to fill the emotional void in her life, and she believes that possessing Kaito’s love will cure her loneliness. In the story, she functions as a central obstacle in the romance between Lucia and Kaito, as her presence drives a wedge between them during Kaito’s amnesia. Her key relationships include her obsessive attachment to Kaito, her conflict with Lucia, who sees Kaito slipping away, and her connection to her older brother Rihito Amagi, a famous conductor who becomes her caretaker. She is also tied to the angelic being Michel, as she is the human half of that entity; Michel can take control of her body, especially during moments of emotional weakness, and her physical collapses often occur when Michel appears or when she feels threatened by Lucia. Over the course of the story, Mikaru undergoes a limited but significant development. In the manga, after Kaito rejects her outright—even when she desperately offers herself to him—she suffers a complete breakdown, which allows Michel to fully seize control. In the end, she is effectively reborn as a pure infant and entrusted to Rihito to raise from the beginning, symbolically resetting her existence and freeing her from the pain and obsession that previously consumed her. Mikaru does not possess combat abilities; her notable traits are her fragile health, her emotional volatility, and her capacity to act as a vessel for Michel’s power, which makes her both a tragic figure and an indirect antagonist within the story.