Aldebaran, commonly called Al, is a human summoned from Japan to the world of Re:ZERO before Subaru Natsuki. He officially serves as Priscilla Barielle's knight, a role he detests, while retaining modern Japanese speech and cultural references. He possesses an Authority that creates localized time loops within a set area, preserving his memories through each reset and allowing him to learn opponents’ tactics through repetition. He also wields earth magic for attack and defense. After surviving a past as a gladiator, he joined Priscilla’s camp and exhibits unwavering loyalty to her despite her demeaning treatment. He commands the shinobi Yae Tenzen, whom he traumatized into absolute submission using his Authority, and she now serves him obsessively. Aldebaran has a connection to Echidna, the Witch of Greed, who named him meaning “Following Star” and whose expectations he both bears and betrays. Despite repeated failures, he is driven by an obsessive will to challenge fate and pursue an unnamed target, vowing to persist even beyond a billion attempts.