TV-Series
Description
Mayu Ōyama is the young daughter of Tochiro Oyama, the brilliant engineer who built the Arcadia, and Queen Emeraldas, a legendary space pirate in her own right. Following Tochiro's death and Emeraldas' departure, Harlock takes responsibility for Mayu, becoming a guardian figure in her life. However, out of respect for Tochiro's final wish, Mayu does not join Harlock aboard the Arcadia but instead remains on Earth, where she lives as a student at a Catholic boarding school. She is often depicted with short blue hair and brown eyes, and she wears a simple uniform with a bow, giving her an innocent and youthful appearance that contrasts with the darker, more weathered world of the space pirates.

Mayu's personality is marked by a quiet resilience and a deep emotional strength. She endures the loneliness of being separated from Harlock and the absence of her parents without bitterness. She treasures the ocarina that Harlock gave her on her seventh birthday, and she often plays a tune on it that has become known as Mayu's Theme, a melody that fans of the series recognize as a symbol of her connection to Harlock and her hope. Despite her tender age, she displays a mature understanding of the sacrifices Harlock makes and the dangers he faces. She does not complain about her situation, even when she is frequently used as a pawn by the Earth government or the alien Mazone, who attempt to capture or harm her in order to lure Harlock into a trap.

Her primary motivation is to honor her father's memory and to live on Earth as he wished, even when that life is difficult or lonely. She understands that Harlock's fight against the oppressive forces threatening Earth is not just for her but for the entire planet, and she takes comfort in the knowledge that Harlock is protecting the world that her father loved. When she feels overwhelmed by the hardships of Earth life, she briefly considers leaving with Harlock, but after learning of her father's true feelings, she resolves to stay and make the best of her life on the planet, promising Harlock that she will remain strong.

In the story, Mayu serves as an emotional anchor for Harlock, grounding his mission in a personal stake. His vow to protect Earth is inseparable from his vow to protect her. The Earth government and the Mazone recognize this bond and exploit it by targeting her, but Harlock and his crew consistently go to great lengths to rescue her whenever she is captured. Even when she is taken prisoner by the Mazone, Harlock vows to journey to the ends of the universe to bring her home safely. This dynamic reinforces the themes of loyalty and found family that run throughout the series.

Her key relationships are with Harlock, who acts as her surrogate parent and protector, and with her parents, whose memory shapes her identity. Although she never appears aboard the Arcadia as a crew member, her presence in Harlock's thoughts gives his rebellion a deeply personal dimension. Her bond with Harlock is built on mutual trust and affection; she does not question his mission or his absences, and he, in turn, treats her with a gentle seriousness that he rarely shows to anyone else.

Mayu's development is subtle but significant. She begins as a child who relies entirely on Harlock for safety and emotional support, but over the course of the series she grows into a more independent person, capable of making her own choices about her future. She learns to cope with her circumstances and finds strength in the love of those who are far away. She does not possess any combat abilities, special powers, or advanced technology; her strength is purely emotional and symbolic. Her ocarina playing, however, serves as a form of communication and a signal of her presence, a small but meaningful ability that connects her to Harlock across the vast distances of space. Her unique hybrid lineage as the daughter of a human genius and a legendary space pirate, though seldom explored directly, marks her as a bridge between two worlds, and her quiet courage makes her a figure of hope and continuity in the midst of Harlock's endless war.