Grossular is one of the five Chief Officers, the highest-ranking ministers of the ACCA organization. Before rising to this central position, he was the branch manager of the Rox District, to which he is a native. His most distinctive physical feature is his long, flowing gray or silver-white hair, a notable trait that aligns with the traditional, older culture of his home district. In demeanor, he is often described as a silent and enigmatic man, rarely revealing his thoughts openly.

Grossular’s personality is layered, presenting a calm and respectful exterior, particularly towards his subordinates. For instance, he holds a deep respect for Mauve, the Inspection Department Chief, and prefers a gentle, advisory approach when cautioning her, rather than issuing direct commands. He is proud of ACCA as an institution and understands it as the very symbol of the kingdom's peace. However, beneath this composed surface exists a man in a position of profound internal conflict. He is not the true master of his own actions; rather, he acts under the will and instruction of his fellow chief, Lilium. Grossular was manipulated by Lilium and became a puppet who, despite knowing the full scope of Lilium’s plans, felt he had no choice but to follow orders.

His primary motivation throughout the story is the preservation of ACCA and, by extension, the stability of the kingdom. He supports a plan to abolish the Inspection Department, but this stance is part of a larger, more complex design. Grossular is a key architect behind a rumored coup d'état. He intentionally leaked information that Jean Otus, a member of the Inspection Department, was involved with the coup faction to observe how each district would react to the news. Ultimately, his goal aligns with the other chiefs: to prevent Prince Schwan from dismantling ACCA and seizing dictatorial control. To counter this threat, Grossular supports a counter-coup that would place Jean Otus, who possesses royal blood, on the throne as a symbolic figurehead while allowing ACCA to retain true control over the kingdom.

In terms of his role in the story, Grossular serves as a central figure in the political intrigue. He is the one who instructs Nino, from ACCA's Internal Affairs Investigation Division, to monitor and report on Jean Otus directly. Throughout the series, he appears to be in constant opposition to Lilium during the Five Chiefs meetings. However, this is later revealed to be a front; their clashes are partly a show to hide their true coordinated intentions from the other chiefs and from Prince Schwan. His most significant relationships are with Lilium, who holds absolute control over him, and with Mauve, whom he respects and works alongside to ultimately change the direction of the organization's future. He also shares a professional, though initially suspicious, relationship with Jean Otus, whom he ultimately decides to support as a key figure in the coup plan.

Grossular’s character arc involves a transition from a passive puppet to an active agent of change. He confesses that he was once a good person who was respected by his peers, including Mauve and Jean, but was moved by Lilium and became his puppet. Though he wanted to escape this servitude, he was unable to do so until the final stages of the plan. In the end, he successfully rebels against Lilium’s control, striking a decisive blow against the scheme. Following the resolution of the coup, he attempts to abolish the Five Chief system and resign, but is strongly persuaded by Mauve to remain in his role as an advisory minister. His notable abilities are not physical or combative, but political and strategic, specifically his talent for misdirection, surveillance, and orchestrating large-scale organizational maneuvers from within the highest levels of government.