Lala Hiyama is a human woman who wears a bear-like life support suit to sustain herself. She was a member of the original Immortal Ship Committee, a former Gardes pilot, and the best friend of the legendary ace pilot Hiroki Saitou. She participated in the exploration mission to an alien artifact where the Kabizashi weapons were first discovered six hundred years before the main events of the story. After Hiroki had a falling out with Captain Kobayashi and the committee, Lala left the committee as well.

In the present day, Lala serves as the dorm mother for the Gardes pilot cadets, including the protagonist Nagate Tanikaze. Because Nagate is a clone of her old friend Hiroki, she takes a personal interest in looking after him, making sure he eats properly, cleaning his room, and speaking with him often. She is rational, kind, and nurturing by nature, but she has a notable quirk: she becomes fiercely angry if anyone addresses her directly by her given name, Lala.

Physically, Lala is very strong, possibly enhanced by her life support suit. In one instance, she grabbed a fallen security officer and hurled him like a log to knock down snipers. She also has an artificial right arm, a result of past events. Her appearances are that of a bear, but this is only the suit; her true human form is hidden within. Despite her gentle demeanor with the cadets, she remains capable and experienced, having been a pilot and a security chief in Sidonia. Her role in the story is primarily that of a caretaker and a link to the past, providing Nagate with guidance and a sense of connection to Hiroki.