Aquilina Schiller, also known as Lina, is introduced as a new coach for the Raimon team during the battle against the Alius Academy. She is the daughter of Astram Schiller, the wealthy head of the Schiller Group who masterminded the Alius Academy project as a means of seeking revenge for the death of his son, Xavier. Aquilina is also the adoptive sister of Xavier Foster, a boy whom her father groomed to be the captain of the team Genesis due to his resemblance to her deceased biological brother.

Aquilina is a tall, beautiful, and enigmatic woman with dark green or black hair that reaches her shoulders and sharp blue eyes. Her outward personality is serious, strict, and disciplined. She often appears cold and unemotional, making decisions that seem ruthless and without regard for the players' feelings. This demeanor causes many members of the Raimon team, particularly Kevin Dragonfly, to distrust her and be unhappy with her leadership. Only a few, like the ever-optimistic captain Mark Evans and the strategist Jude Sharp, maintain faith in her, sensing a hidden depth behind her stern facade.

Despite her cold exterior, Aquilina is deeply caring and motivated by a desire to protect the children under her charge. Her most controversial decision was expelling the star forward Axel Blaze from the team. While the team saw this as a cruel and illogical act, it was later revealed that she did so to protect Axel and his sister from the clutches of the Alius Academy and her own father's manipulations. Her true motivation for becoming Raimon's coach was to stop her father's reign of terror and save him from his own destructive path of revenge. She is willing to be hated by the team if it means achieving this greater good and protecting the young players.

Aquilina's role in the story is central to the Alius Academy saga. She is the strategic mind guiding Raimon to become strong enough to challenge the alien-themed teams, culminating in a final match against Genesis. Her deep personal stake in the conflict is revealed when the team's managers discover that she is Xavier Foster's sister. After the defeat of Genesis and the redemption of her father, Aquilina chooses to stay with the brainwashed children of the Alius Academy to care for them and help them recover.

Following these events, Aquilina continues her involvement with football. She becomes the coach of Neo Japan, a team assembled specifically to challenge Inazuma Japan for the right to represent the country in the Football Frontier International tournament. Although her team loses, she demonstrates her tactical acumen and earns the respect of the national team. In the Inazuma Eleven GO timeline, Aquilina has matured into a more maternal figure, becoming the director of the Sunshine Garden orphanage, also known as Don Sol. In this role, she continues to support young talent, and it is she who brings the defender Aitor Cazador to Raimon after recognizing his potential.

Aquilina is a highly intelligent and skilled strategist, described as sharp, cunning, and analytical. Her notable abilities lie in her coaching and tactical mind, which allow her to identify player weaknesses, formulate effective game plans, and push teams to their limits. In the context of the video games, she possesses coach skills that can boost the stats of players, particularly those with a Fire element affinity. Her personal philosophy, which initially prioritizes winning above all else, evolves as she rediscovers the joy and spirit of football through her interactions with players like Mark Evans.