TV-Series
Description
Euclase is a supporting character in the manga and anime series Land of the Lustrous. As a Gem, Euclase has a hardness of 7.5 on the Mohs scale and serves as the secretary to Kongo, the enigmatic leader of the Lustrous. Their role is primarily administrative and strategic, managing the patrol shifts against the Lunarians, the recurring antagonists who seek to capture the Gems for their decorative value. Known for a calm, composed, and highly responsible nature, Euclase is a senior figure within the community and is trusted with the vital task of maintaining order and organizing missions.

Euclase possesses a personality marked by diligence, compassion, and a strong preference for diplomatic solutions over aggressive actions. As a secretary, they exhibit acute perceptiveness, often being one of the first to notice underlying issues or behavioral changes in their fellow Gems, such as the troubling transformation of Phosphophyllite after their missions to the moon. Euclase is defined by a principle of efficacy and reason, refraining from unnecessary or rash actions that would not yield optimal results. This pragmatic yet caring demeanor extends to a protective instinct, particularly towards younger or more vulnerable Gems like Phosphophyllite.

Throughout the story, Euclase's role evolves from a background administrator to a central figure in the Gems' leadership during times of crisis. Their primary motivation is the preservation and stability of Gem society. Even when faced with overwhelming conflict, Euclase's first instinct is to seek a reasoned path forward. In a pivotal moment after Kongo reveals his true nature, it is Euclase who steps forward to propose a fresh start, advocating for learning from the past rather than being paralyzed by it. Later, when the Gems debate the fate of a shattered Phosphophyllite, Euclase advocates for reassembling the pieces to negotiate a resolution, demonstrating their unwavering commitment to communication and non-violent solutions even towards an enemy.

Euclase’s most defining act comes during the final, devastating confrontation with Phosphophyllite. Standing amidst the destruction of their comrades, Euclase lowers their weapon and kneels before Phos, formally conceding defeat. Rather than fight, Euclase asks to be taken to the moon to negotiate a solution, pleading that given their long lives, they have the luxury of time to find an answer. This act of surrender is not born of cowardice but of supreme rationality and a final, desperate hope for dialogue. Tragically, Phos responds by shattering Euclase's head and stepping over their body, symbolizing the complete breakdown of the diplomacy and compassion Euclase always championed.

In terms of notable abilities, Euclase's greatest strength is their intellectual and strategic acumen. They are exceptionally talented at calculations and predictions, which allows them to accurately forecast Lunarian attacks and manage the Gems' defensive schedules with high efficiency. Beyond this administrative genius, Euclase is also a capable fighter, routinely participating in patrols and wielding a sword in battle. However, their key relationships are defined by their role as an advisor to Kongo and their stark philosophical opposition to the increasingly violent and irrational Phosphophyllite, representing the voice of measured order in a world descending into chaos.
Cast