TV-Series
Description
Gruier Serenity, the Stowaway Princess, serves as the seventh princess of the Serenity Planet Commonwealth's royal family. Raised within the palace, she embodies grace yet remains approachable, never allowing her royal status to impede social ease. Her sheltered upbringing initially fostered naivety, sometimes manifesting as a tendency to withhold critical information from allies—a habit causing her personal remorse but diminishing as she adapted to her responsibilities.

She stands 140 centimeters tall and weighs 34 kilograms, with blonde hair and blue eyes. Her hairstyle varies between formal braided tails or buns and casual settings. At Hakuoh Academy, she wears the standard pink middle school uniform with a blue skirt, adding a black Yacht Club hoodie for club activities. Formal events see her in elaborate white gowns adorned with frills, ribbons, tiaras, and white roses.

Her skills include theoretical dinghy piloting knowledge from Yacht Club simulations and operational experience on systems aboard both the luxury yacht Odette II and the pirate vessel Bentenmaru, despite an inability to swim. Royal education honed her diplomacy and lie detection abilities, allowing her to discern truthfulness unless the speaker believes their own falsehood. Additional talents encompass artistic painting and a noted proficiency for stowing away on spacecraft, a recurring behavior.

Her narrative involvement begins by secretly boarding the Bentenmaru using a special ring from Gonzaemon, Marika Kato's father. Her covert mission is to find the Golden Ghost Ship and destroy the artificial womb used for royal births, aiming to end her family's political conflicts without their knowledge. This goal initially strains her relationship with her sister, Grunhilde Serenity, due to opposing views on the monarchy, though they later reconcile. Gruier conceals her mission's true purpose from Marika and the crew during this period.

After resolving the Golden Ghost Ship incident, Gruier actively assists Marika, providing intelligence, crafting disguises, and participating in spacecraft operations. She increasingly disregards royal protocols to support these efforts, demonstrating adaptability and a willingness to employ underhanded tactics. Her friendship with Marika evolves from cautious interaction into mutual respect, offering Gruier freedom from royal formalities. She also forms a budding friendship with Chiaki Kurihara, marked by more mature conversations than those with Marika.

Notable trivia includes her physical resemblance in casual attire to Princess Serenity from Sailor Moon, primarily distinguished by her braided hair partitions. Marika coined the nickname "Stowaway Princess" (密航王女) early in their acquaintance, referencing her repeated covert boarding of vessels; it later became the title of her anime theme song.