Eno, the Witch of the Grotto, is an immortal witch resembling Azusa Aizawa. She presents as a young woman of roughly nineteen with dark pink or red hair and yellow or olive eyes, matching Azusa's height despite her significant age.

Operating from her northern grotto, Eno specializes in brewing potions and crafting items with diverse effects. She initially disguised herself as an old woman to aid nearby townsfolk, sparking rumors that reached Azusa. After Azusa and companions revealed her disguise, Eno retreated home. Azusa later advised her to sell creations publicly while maintaining a character portrayal to manage Eno's social anxiety. This strategy boosted her popularity and profits, though demand eventually outstripped her production capacity.

Eno's social anxiety drives her preference for word-of-mouth recognition over personal exposure, shaping her business and community interactions through disguises and indirect methods. She developed a professional rivalry with Halkara due to shared interests in potions and items, leading to occasional borrowing or adaptation of ideas. Eno expresses gratitude to Azusa for the guidance that enhanced her business success.

Eno possesses no documented combat abilities or direct battle participation. Her expertise remains exclusively focused on potion craftsmanship and item creation.