Muninn appears as one of Odin's paired ravens in the Record of Ragnarok series, distinguished by black feathers contrasting with Huginn's white. Both possess the ability to speak human language despite their avian form. Their personalities are proud and talkative; they view humanity as inferior and leverage their status as Odin's companions, though inherent physical vulnerability makes them cautious, silencing them when sensing threats.

Muninn and Huginn consistently attend significant divine gatherings. They were present 4000 years ago at the Gods' Council debating humanity's fate and millennia later when Brunhilde proposed the Ragnarok tournament. During that later council, they dismissed her proposal, expressed skepticism about human capability, questioned her methods, and doubted humans could defeat gods.

Throughout the Ragnarok matches, they serve primarily as observers and commentators. They witnessed Thor's battle against Lü Bu, reacting with surprise when Lü Bu blocked Thor's Geirröd Thor's Hammer attack, and continued observing subsequent rounds, including the second match between Zeus and Adam.

Their abilities stem from their nature as Odin's ravens: an exceptionally long lifespan exceeding 4000 years and the capability for human speech granted to them by Odin. Their role aligns with their mythological roots as scouts and informants who traverse the world reporting back to Odin, embodying concepts of memory and thought as suggested by their names. Muninn's presence underscores Odin's watchful nature, functioning as extensions of the All-Father's perception during the tournament.