Arsène Lupin I is a supporting character in the original net animation Lupin Zero. He is the grandfather of Arsène Lupin III and the father of Arsène Lupin II, placing him at the top of the family line of master thieves. In the series, he appears as an elderly gentleman with short gray hair and blue eyes, and is typically dressed in a vest, bowtie, top hat, and cape, with a beard completing his distinguished appearance. His role in the story is tied to the legacy of the Lupin name and the succession of the family's thieving tradition. In the episode titled The Grandson of the First Vies for Succession, he sends two mysterious messengers to approach Lupin III with a threatening invitation, drawing his grandson into a confrontation that tests his worthiness to inherit the title of Lupin. This encounter forces the young Lupin III to reckon with his grandfather's expectations and the weight of his family's criminal heritage. As the original Arsène Lupin, he is the foundational figure whose exploits established the reputation that his descendants seek to uphold or surpass. His presence in the story serves as a direct link between the legendary past of the Lupin family and the emerging identity of Lupin III. The available information does not provide further detail on his personal motivations, internal development, or specific abilities beyond his position as a patriarch who actively monitors and challenges his grandson's progress.