TV-Series
Description
Conrad Weller is a central figure in the story, known for his calm demeanor, unwavering loyalty, and exceptional swordsmanship. He serves as one of the primary protectors and most trusted advisors to the series' protagonist.

Conrad is the second son of the former Demon Queen, Cecilie von Spitzweg, making him a prince of the Mazoku demon race. His father is Dan Hiri Weller, a renowned human swordsman from the royal family of Big Cimaron. This mixed heritage gives him a unique perspective on the relationship between humans and Mazoku. He is the half-brother of both the stoic and responsible Gwendal von Voltaire and the hot-headed and proud Wolfram von Bielefeld. Despite being over a hundred years old, he has the appearance of a man in his late twenties. He has dark brown hair and light brown eyes with specks of silver.

Conrad's personality is marked by a rare combination of rationality and deep-seated passion. He is even-tempered and level-headed, especially when compared to his two brothers. He prefers to approach situations with logic and does not let his emotions easily distract him. However, this placid exterior hides a fierce and reckless protector. When King Yuri or his brothers are in danger, Conrad becomes utterly ruthless and will take extreme risks without a second thought for his own safety. He possesses a subtly skewed sense of humor and can be genuinely warm and affable. He is also a man who accepts responsibility for his actions without complaint, even willing to resign himself to punishment if he believes he deserves it, regardless of his intentions.

Conrad's primary motivation stems from a promise he made long ago. At the request of Suzanna Julia von Wincott, he was entrusted with the soul of the next Mazoku king. He carried this soul to Earth to ensure it would be born into a safe life. He was present at the birth of Yuri Shibuya, where he suggested the name based on a word from his homeland that means July. Because of this, Yuri considers Conrad his godfather, or "Nazukeoya," the person who named him. This deep, personal connection is the root of his absolute devotion. Conrad's mission is to keep Yuri happy and safe, and he is willing to sacrifice anything, including his life and reputation, to achieve that goal.

In the narrative, Conrad acts as a mentor, guardian, and loyal retainer to the newly crowned Demon King. He is often the one to find Yuri when he first arrives in Shin Makoku and helps ground him in the basics of the world, such as teaching him swordsmanship. His loyalty is tested severely when he loses his left arm during a battle while protecting Yuri and is presumed dead. He later reappears, seemingly having betrayed Shin Makoku to join the human nation of Big Cimaron. In reality, this apparent betrayal was a deep cover mission to learn the secrets of the forbidden boxes that could destroy the world, as his lost arm was one of the keys needed to use them. This arc demonstrates his willingness to endure hatred and push away those he loves for the sake of the greater good. He pushes even his best friend, Yozak Gurrier, off a cliff to maintain his cover. After returning to Yuri's side, he states he will accept any punishment, staying true to his principled nature.

Conrad's key relationships define his actions. His bond with Yuri is the most significant, characterized by profound trust and mutual respect. He follows Yuri's orders completely unless they would result in Yuri being hurt. He has a close friendship with the spy and information-gatherer Yozak, having fought alongside him as the only two survivors of the brutal Battle of Lütenburg. With his brothers, he acts as a stabilizing force, balancing Gwendal's stern silence and Wolfram's quick temper.

Throughout the series, Conrad evolves from a man who seems willing to martyr himself for his cause to one who understands that his survival is also vital to those he serves. He learns to fight for Yuri not just by sacrificing himself, but by staying alive to continue protecting him.

As a warrior, Conrad possesses no magic, a rarity among Mazoku nobles. To compensate, he has become a master swordsman, widely acknowledged as the greatest in the Great Demon Kingdom. Despite losing his arm, he eventually receives a new one and continues to be a formidable and legendary fighter on the battlefield.