: The introduction of Marie reinforces the series' ongoing theme of the "Xenos"—monsters with human-like souls—and the moral complexity of Bell’s vow to protect them.
: Unlike typical hostile monsters, Marie is friendly and aids Bell by healing his wounds using her blood and guiding him through the labyrinthine waterways. 4 : Mermaid: The Girl of Water City
: The episode serves as a precursor to the "Labyrinth Arc" climax, showcasing Bell's increasing maturity and his ability to trust and collaborate with non-human allies even in life-threatening situations. : The introduction of Marie reinforces the series'