Beta is a pet puppy companion to protagonist Rem Ayanokōji, functioning as a supernatural support entity. This character transforms from an ordinary small dog into a larger, formidable wild canine during confrontations with adversaries threatening Rem's objectives in supernatural investigations. Beta demonstrates specialized capabilities in detecting and tracking spectral entities like ghosts and spirits, operating across both physical environments and dreamscapes to assist paranormal investigations. The character consistently partners with Alpha, a cat companion who similarly transforms during engagements, forming a complementary support unit under Rem's direction. Beta's origins and background remain undisclosed, maintaining a consistent role throughout appearances without evolution, personal narrative arcs, or expanded backstory. Interactions focus exclusively on operational cooperation with Rem and Alpha during supernatural engagements, with no significant relationships beyond this dynamic.