Leonardo Stoller, a demi-human engineered during the Gaz Empire war for hazardous duties such as frontline combat, faces pervasive human prejudice in the conflict’s aftermath due to his hybrid origins. This ostracization starkly contrasts with the unwavering respect shown by Alberic Gilette, leader of the Gillette Corps, who recruits Leonardo as an equal. Alberic’s mentorship forges Leonardo’s fierce loyalty and dedication to the corps, anchoring his post-war identity.

Within the group, Leonardo evolves into a strategic thinker, meticulously analyzing Chaika Trabant’s motives and theorizing about her counterparts. His wartime genesis and post-war struggles fuel a methodical, questioning mindset, driving him to unravel the enigmas behind Chaika’s objectives while balancing caution with relentless curiosity.