Reginleif ranks seventh among thirteen Valkyrie sisters. Her name means "Daughter of the Gods" or "Power Trace," signifying her divine heritage and bond as Adam's partner. She has neck-length black hair cut in a bob, turquoise eyes, and wears rectangular glasses. Her attire resembles a medieval scholar, complete with a cape and scholar's hat.

She shows fierce loyalty to her sisters and backs Brunhilde's plan for Ragnarok. Reginleif tutored her youngest sister, Göll, sharing the occasional frustration with Göll's anxious nature. She attended the Gods' Council with her sisters to strategize against the gods before Ragnarok.

In Ragnarok's second round, Reginleif became Adam's Völundr. She arrived mid-battle riding a Pegasus before landing in the arena. She explained their hearts required synchronization to succeed. Upon touching fingers, she transformed into a knuckleduster for Adam's right hand, amplifying his punches—a moment echoing Michelangelo's *The Creation of Adam*.

As the conscious knuckleduster during Adam's fight against Zeus, she witnessed his Divine Reflection copying Zeus's techniques, his subsequent blindness from overuse, and his final death while standing. After Adam fell, both his body and the knuckleduster crumbled. Reginleif manifested briefly, smiling and reaching for his hand in respect before vanishing with him.

A demigod, Reginleif possesses semi-immortality and divine physiology, granting physical prowess beyond mortals and immunity to non-divine weapons. Her Völundr ability lets her transform into a weapon matching her partner's needs. She is a skilled horseback rider, demonstrated by her Pegasus arrival. The Völundr's "Common Destiny" binds her fate to her partner in battle.