**Height:** 173 cm (5'8") Aldebaran, commonly known as Al, is Priscilla Barielle's knight, though he claims to just be a subordinate. He has a frivolous personality and acts aloof, but shows insecurity regarding his disfigured face and wears a helmet to conceal it. Due to that, he is a man of both eccentric appearance and behavior.

Spoiler

Like Subaru, he is revealed to be from Japan and was summoned roughly 18 years before Subaru. Shortly after he was summoned, he lost his left arm in an unfortunate incident in the Empire of Vollachia.