Matthias Hildesheimer is the main protagonist of the anime The Strongest Sage With the Weakest Crest. He is the reincarnation of a legendary sage named Gaius, who lived more than five thousand years before the story begins. In his previous life, Gaius possessed the First Crest, which granted immense magical augmentation but was ill-suited for close-quarters combat. Dissatisfied with this limitation, he developed a reincarnation spell and was reborn as Matthias, the third son of the Hildesheimer baronet family. His new life granted him the Fourth Crest, a mark specialized for close-combat magic, which he had always desired. However, he soon discovers that in the present era, humanity’s knowledge of magic and swordsmanship has drastically declined. The Fourth Crest, once celebrated as the most powerful, is now dismissed as the Weakest Crest, and basic spells that were common in his past life have been forgotten.

Matthias retains all the memories, skills, and vast magical knowledge from his time as Gaius. This makes him exceptionally powerful compared to his contemporaries, but also leaves him somewhat detached from modern social norms. He tends to be analytical, strategic, and goal oriented, often explaining ancient magical principles to those around him. Because of his anti-social lifestyle in his previous life, he can still react with surprise or embarrassment in social situations, though he is far from emotionless. He openly admits that his primary reason for helping the kingdom is to gain strength for himself, but his actions show a genuine concern for his companions and a desire to protect humanity from looming threats.

Matthias’s motivations stem from his awareness of impending dangers. He knows that powerful monsters from outer space—demons—have been manipulating human history to weaken magical capabilities, and he intends to counteract this. He enrolls at the Second Royal Academy in the capital at the age of twelve, where he quickly demonstrates his unmatched abilities. His role in the story is that of a reawakened sage who must revitalize the world’s magical knowledge and confront the demonic forces working in the shadows.

Key relationships define his journey. He forms close bonds with Lurie Abendroth, a kind noble girl with the First Crest, and Alma Lepucius, a talented archer with the Second Crest. Matthias trains them in advanced techniques, and they become his trusted allies and students. He also reunites with Iris, a powerful Dark Dragon who served him in his previous life as Gaius. Iris recognizes Matthias’s true identity and travels with him, eventually taking a human form. Though she is ancient and immensely strong, she is often comically airheaded and fiercely loyal.

Over the course of the story, Matthias transitions from a solitary sage solely focused on personal power into a leader and teacher who systematically reforms the kingdom’s magical education and combat standards. He shatters the prejudices of those who underestimate his crest and uses his expertise to enchant equipment, perform chantless magic, and adapt ancient spells for modern use. His notable abilities include mastery over all forms of magic, exceptional swordsmanship, the capacity to enchant weapons and items, and the knowledge of rare languages such as Dragonese. He is also a skilled strategist, able to analyze threats and devises effective countermeasures. Through his actions, Matthias not only grows stronger himself but also elevates the capabilities of those around him, preparing humanity for the battles to come.