Beta is a supporting character in the original video animation series Dream Hunter Rem, serving as one of two animal companions to the protagonist, Rem Ayanokouji. As a young puppy in the real world, Beta is small and appears to be an ordinary pet, but his true nature is revealed when he accompanies his owner into the dream dimension. In this supernatural realm, Beta transforms into a large, fierce wild dog or combat hound, capable of fighting alongside his human allies against the demons that invade people's nightmares.

Within the narrative, Beta functions as a vital assistant and guardian. His primary role is to provide support during missions where Rem hunts demons that turn dreams into deadly nightmares. Unlike his counterpart Alpha, a kitten who becomes a wildcat in dreams, Beta possesses a specific and notable ability to track ghosts and spirits. This tracking capability makes him indispensable for locating ethereal threats and navigating the often chaotic and deceptive landscapes of the dream world. His transformation is not merely a change in size but also a shift in demeanor, becoming fierce and combat-ready when his mistress is in danger.

Beta's relationship with Rem is that of a loyal pet and trusted partner. Their bond is central to his character, and his motivation is intrinsically tied to protecting her and aiding her mission. He is part of a small, close-knit team that includes Rem, Alpha, and their human allies such as a martial monk and a parapsychologist. His interactions are primarily with Rem and Alpha, forming a trio of dream hunters who rely on each other's unique strengths. While the series focuses on Rem's growth and battles, Beta's development is largely static, defined by his unwavering loyalty and consistent effectiveness in his support role. His presence provides both practical assistance in combat and a reliable, comforting constant for Rem across the various installments of the OVA series.