Marine Ryuzaki is one of the three main protagonists of the anime Rayearth, known as the Magic Knight who represents the water element. She is a fourteen-year-old eighth-grade student from a wealthy, respected family; her father is a prominent businessman, and she attends a prestigious all-girls school. Marine has a tall, elegant appearance with long, flowing azure blue hair and blue eyes. Despite her graceful looks, she possesses a quick temper and is initially portrayed as the most skeptical and reluctant of the three girls when they are first transported to the magical land of Cephiro. She is under pressure to return home for a fencing competition and is uncertain about the quest thrust upon them.

Marine’s personality is defined by her fiery, no-nonsense attitude, which often provides comic relief through her exasperated interactions with the creature Mokona. However, as she grows closer to her companions Hikaru Shidou and Fuu Hououji, Marine becomes deeply protective of them, taking on a big-sister role within the group. Her motivations shift from a desire to quickly return home to a genuine commitment to saving Cephiro and supporting her friends. She develops a strong bond with the two other Magic Knights, particularly Hikaru, whose determination inspires her. Marine also forms friendships with the twin rulers of Chizeta, Tatra and Tarta, whom she defeats in sword fights, and in the manga she shares a special, implicitly romantic connection with the boy Ascot.

As a Magic Knight, Marine pilots a water-elemental Mashin (Rune-God) and wields water-based magic. Her signature spells include the Water Dragon and Azure Hurricane, which she uses in battle against the forces threatening Cephiro. Her fencing skills, honed by her extracurricular activities, also serve her well in combat. Throughout the series, Marine’s character evolves from a self-centered and hotheaded girl into a more mature and dependable warrior, learning the value of teamwork and sacrifice. By the second season, she displays greater emotional depth and responsibility, though she retains her spirited and occasionally impulsive nature. Her abilities as a Magic Knight are crucial to the group’s success, and her growth as a person is central to the story’s themes of friendship and self-discovery.