Julius Juukulius originates from the Re:Zero universe, serving as a knight to Anastasia Hoshin and a member of Lugunica's Royal Guard. Born to a noble father who relinquished his status to marry a commoner mother, he became an orphan after his parents died in a flash flood. His uncle, Alviero Juukulius, adopted him, integrating him into the noble House Juukulius alongside his cousin Joshua. His upbringing emphasized rigorous swordsmanship training to uphold the family's legacy of exceptional knights. Initially presented with a strict and prideful demeanor, Julius values chivalry and nobility above all, leading him to clash with Subaru Natsuki after Subaru insulted the Royal Guard. This culminated in a public duel where Julius decisively defeated Subaru to uphold knightly honor; his underlying intent was to prevent Subaru's potential execution by the Royal Army. Despite the confrontation, Julius held no personal grudge and later expressed hope for Subaru's growth. Beneath his composure lies deep-seated insecurity stemming from childhood trauma, noted by Reid Astrea. Julius relies heavily on bonds with others to fill emotional voids, striving to embody an idealized knightly image to inspire. His idealism extends to believing in inherent goodness, even in adversaries like the Witch Cult, prompting him to assist Subaru in rehabilitating former Sin Archbishop Spica. His combat prowess is multifaceted. As the "Spirit Knight," he wields the Divine Protection of Gathering Spirits, forming contracts with six elemental spirits: La, Kua, Aro, Ik, In, and Nes. These spirits enable versatile magic, including weapon augmentation (Clarista), elemental beams (Al Clarista), armor-piercing strikes (El Clausel), and large-scale firestorms (Fell Goa). He also possesses sensory-sharing abilities (Nect) and exceptional swordsmanship, ranking second only to Reinhard van Astrea in Lugunica's Royal Guard. These capabilities were temporarily nullified when the Sin Archbishop of Gluttony devoured his name, erasing others' memories of him except Subaru's. In the Isekai Quartet crossover, Julius interacts with characters from multiple isekai series within a school setting. During a field day event, he initially greets Subaru with formal knightly etiquette. In a cavalry battle pitting Class 1 against Class 2, Julius teams with Reinhard, Felt, and Eris against Subaru's group. When teachers join the fray, Julius uses light magic to blind them, shielding Subaru's team. He later suggests tactical coordination with Subaru against a common enemy, acknowledging Subaru's determination to protect Emilia. This marks a shift from their earlier antagonism to mutual respect, with Julius observing Subaru's evolving sense of knighthood. His relationships are defined by loyalty and evolving dynamics. He shares a bond of trust with Anastasia, respects Reinhard as a friend and comrade, and reconciles with Subaru after their initial strife, notably during joint efforts against the Witch Cult in Arc 5. Ricardo Welkin sacrifices an arm to protect Julius during their battle against Roy Alphard. Julius sustains permanent facial scarring from a duel with Reid Astrea in Arc 6, symbolizing his acceptance of flaws and commitment to rebuilding severed bonds. Later, in Arc 8, he adopts Kararagian attire—kimono, haori, and hakama—during missions in Vollachia, reflecting adaptability beyond his formal knight identity.