Corinna, Benno's younger sister, was raised by him following their parents' death in her childhood. As the original heiress to the Gilberta Company, she endured strict merchant training under Benno to prepare for leadership. Unable to evade a guildmaster's son's marriage proposal by leaving the city like her older sister, she was persistently courted by Otto, a former traveling merchant. Otto eventually persuaded her into marriage, and Corinna developed genuine affection for him, resulting in a loving relationship. They live on the Gilberta Company building's third floor with their two children, Renate and Knut. During the anime's events, Corinna is expecting her first child, due in winter.

Corinna possesses pale cream hair, often styled in a braided updo, and silvery gray eyes. Her noted beauty includes an hourglass figure, complemented by a gentle, feminine demeanor that makes her approachable; her expressions openly reflect her emotions. Beneath this warmth lies sharp business acumen and decisive instincts rivaling Benno's. She strategically leverages her personality to extract commercially valuable information during conversations, demonstrating a willingness to use subtle manipulation for business gains. This indirect approach contrasts with Benno's directness, making her a formidable negotiator.

She co-manages the Gilberta Company with Otto. After Benno founded the Plantin Company and departed, Corinna fully assumed leadership. Her tactics include skillfully guiding discussions to obtain information without offering compensation, exemplified when she elicited details about innovative stitching techniques from Tuuli and Effa. Myne considers Corinna a more intimidating business partner than Frieda due to this effective style. Corinna remains deeply involved in design and sewing, displaying enthusiastic passion when discussing these topics. She occasionally exhibits pensive concern, such as questioning Otto's satisfaction with his gate guard duties before his transition to military accounting.

Corinna maintains close family bonds. She trusts Benno's business judgment, acknowledging his role in mentoring both her and Myne. Her relationship with Otto features mutual support, with Otto actively advocating for her interests within the merchant guild. Tuuli and Effa admire Corinna as an aspirational figure in sewing, unaware of her shrewd business tactics. Her role expanded as she balanced company management with motherhood after Renate and Knut's births.