TV-Series
Description
Aldebaran, commonly called Al, is a human summoned from Japan to the world of Re:ZERO roughly 18 years before the main story, making him approximately 36-37 years old. He officially serves as Priscilla Barielle's knight, a role he detests, while retaining modern Japanese speech and cultural references. His past includes a decade of enslavement as a gladiator in the Vollachian Empire, forging exceptional combat instincts through survival combat.

After escaping the arena, he joined Priscilla's camp. He exhibits unwavering loyalty to her despite her demeaning treatment, frequently acting as her strategist and enforcer. He wears a distinctive helmet and wields the Blue Dragon Sword as standard equipment.

Aldebaran possesses an Authority—a unique ability he identifies as such—which manipulates time within a limited area called his "territory." This Authority randomly assigns individuals within it as either "Victim" or "Aggressor." When designated the Victim (his most common role), time loops upon his death, resetting to the Authority's activation point. This allows him to learn opponents' tactics through repetition, though each death causes excruciating agony. When designated the Aggressor, time loops upon his or the victim's death, but only the victim retains memories across loops, often driving them to insanity. The Authority's activation requirements remain unspecified.

His capabilities include Earth Magic, specifically the spells "Dona" (firing stones) and "El Dona" (raising earth barriers). He also deploys "Ol Shamak," an anti-Witch spell that immobilizes targets and blocks magic use by sealing their Gate. In combat, he demonstrates superhuman physical attributes, analytical prediction refined through looping, instinctive action, aura projection inducing psychological pressure, and extrasensory perception to gauge strength. He carries resistance to fear, madness, soul, mind, and poison manipulation due to his Witch Factor.

Recent developments involve his subjugation of the shinobi Yae Tenzen. After her assassination attempt on Priscilla, he used the Aggressor role of his Authority to traumatize her into absolute submission. Yae now serves him, motivated by a desire to ensure his death to escape her terror. Aldebaran leverages her skills, particularly her mastery of the Steel Thread Technique, to advance his objectives.

A hidden prologue reveals his connection to a Witch (implied to be Echidna), who calls him the "Following Star" for bearing yet betraying her expectations. She states his origin stems from a failed outcome related to Natsuki Subaru, directly linking his existence to Subaru's actions in an alternate timeline. This encounter underscores Aldebaran's determination to "kill" the Witch despite repeated failures, driven by an obsessive will to challenge fate.

His recent activities focus on fulfilling a mission tied to this confrontation, utilizing Yae's abilities and his Authority to manipulate events. He maintains his position as Priscilla's knight while pursuing this goal, often displaying a cynical yet resilient demeanor shaped by years of suffering and looping.