Ermengarde Johannitz, commonly called Ermy, serves as a Reasoner at Basion Academy where she operates advanced mecha units known as Strains. She belongs to Lottie Gelh's elite Space Squadron. Ermy possesses distinct pink hair and golden-yellow eyes, often accentuated by stockings and a mole. She exhibits a preoccupation with body image, voicing unwarranted concerns about her weight while actively promoting health-conscious diets and exercise. Despite this advocacy, she struggles to resist desserts.

Ermy maintains a close friendship with fellow squadron member Martha Shoebbeypower, their bond highlighting stark contrasts: Martha embraces a masculine appearance, physical strength, and meat consumption, while Ermy focuses on feminine beauty standards and dietary restraint. They are consistently depicted together, underscoring their strong connection.

Beyond dietary habits, Ermy displays kindness and helpfulness toward peers. She lacks arrogance despite her acknowledged beauty and remains dedicated to her Reasoner duties, piloting Strains during military engagements alongside her squadron.