Beatrix Monroe is a human student at the magical academy within Ariadne city-state, training to become a mage knight. She serves as Emily Sevensheep's dedicated partner, a bond forged since childhood where Beatrix consistently assumes protective and secretarial duties for Emily. Her demeanor remains reserved and cautious, always prioritizing Emily's safety in perilous situations.

Her pure human ancestry traces back to Megalomesembria, granting her magic the unique capacity to harm demons, proven during Cosmo Entelecheia's assault at the Megalomesembria Ball. Beatrix wields swordsmanship, broomstick cavalry combat, and ice magic, channeling the latter to reinforce her Ariadne Greatsword in battle.

After defeating a Griffin dragon, Beatrix joins Yue Ayase and Collet Farandole as Ariadne's representatives in Ostia. She later aids Ala Alba against Cosmo Entelecheia. While shielding Yue in combat, Beatrix suffers petrification alongside Yuna Akashi and Sayo Aisaka, reverting to normal only after the conflict's end.

In the ANIME FINAL movie, Beatrix contributes to the collective magical effort preventing Mars's collision with Earth. Following the successful fusion of Earth and Mars into a new world, she shops with Emily and Collette, encountering Yue and expressing appreciation for the transformed world.

Beatrix possesses dark blue hair and orange eyes, consistent in all depictions.