Carl Rosenthal, sole heir to the Rosenthal Corporation, inherits his father's bitter rivalry with Harry Burnsworth and the Burnsworth conglomerate. Childhood trauma profoundly shapes his worldview: abandoned in a well at age six by mocking stepsisters, he develops crippling claustrophobia and endures overnight entrapment. His mother, a club hostess married briefly to his father, offers no care, cementing his deep distrust and disdain toward women as agents of pain and betrayal.

Meeting Kajika Burnsworth challenges Carl's misogyny. Her persistent kindness sparks genuine affection, shifting his perspective. He enters as the third suitor in Harry Burnsworth's orchestrated "marriage game," where Kajika must select a husband from preselected candidates. As their bond deepens, Carl uncovers her secret identity as the rightful heir to Raginei, a Southeast Asian kingdom in turmoil. He dedicates himself to guarding this secret, believing it essential for her safety.

During Raginei's political coup, Carl becomes trapped amid the chaos. He navigates the crisis alongside Kajika and key allies, demonstrating fierce loyalty and confronting danger directly. Motivated by Kajika's peril, he overcomes his claustrophobia in a critical enclosed-space scenario, marking a pivotal evolution in his character.

Physically, Carl presents as an adult male with blonde hair cropped at his ears and blue eyes, typically attired in formal suits and ties. His arc concludes with unrequited love; he accepts Kajika's choice of another suitor while maintaining a steadfastly protective stance toward her.