Yukiko Kudo, born Yukiko Fujimine in Tosa Province (modern Kochi Prefecture), gained fame as a talented actress during her time at Teitan High. Her breakthrough came playing Otome in a historical drama about Sakamoto Ryoma, earning international recognition. She retired unexpectedly upon marrying mystery novelist Yusaku Kudo, though maintained film industry connections. After inadvertently solving a criminal case on live television using clues from Yusaku, she earned the nickname "Night Baroness," inspired by one of his fictional characters. To prepare for an acting role, Yukiko trained under a renowned stage magician and disguise artist. There, she met actress Sharon Vineyard, forging a close friendship through their shared mastery of disguise. Yukiko stayed in contact with Sharon until her supposed death and attended her funeral, an event marred by scandal involving Sharon's daughter, Chris Vineyard. Learning later from her son Shinichi Kudo about Sharon's true identity as Vermouth and her role in the Black Organization deeply troubled Yukiko. She confronted Vermouth directly to verify the truth and protect Ai Haibara from the organization. Personality-wise, Yukiko displays a youthful, exuberant demeanor and attention-seeking behavior. She exhibits jealousy over Yusaku's occasional flirtations and impulsiveness, notably through reckless driving. She reacts strongly to age references, insisting on being called "onee-san" instead of "oba-san." Underneath this, she shows deep loyalty, readily traveling to assist family and friends. She frequently teases her son Shinichi but cares deeply for his well-being. Yukiko takes significant pride in her acting and disguise abilities, enabling convincing impersonations, even of close family. Her significant involvements include first appearing disguised as Fumiyo Edogawa, claiming to be Conan Edogawa's mother. She later secretly returned to Japan after quarreling with Yusaku, encountering Ran Mouri and Conan. Yukiko helped deflect Ran's suspicions about Conan by fabricating an elaborate family relation. During the Bell Train arc, she posed as a visitor to Subaru Okiya. On the Bell Tree Express, she collaborated with Conan and Okiya to thwart Bourbon and Vermouth, deceiving the Black Organization into believing Sherry died. Yukiko physically removed Haibara from danger and engaged Vermouth as a distraction, securing Vermouth's promise to cease targeting Sherry. Yukiko also disguised herself as Yusaku to attend the Macademy Awards. After returning home, she assisted Akai Shuichi in reapplying his Subaru Okiya disguise. She nearly slipped in revealing Conan's identity as Shinichi to FBI agents. During the events of Episode One: The Great Detective Turned Small, Yukiko appeared with Yusaku in their "Night Baron" and "Fumiyo Edogawa" disguises, referencing their earlier ruse. She maintains a close friendship with Eri Kisaki despite their high school rivalry in the Miss Teitan Election. Yukiko openly considers Ran Mouri an ideal match for Shinichi. Her relationship with Shinichi involves frequent teasing but underlying support, while her dynamic with Yusaku combines affection with playful jealousy over his interactions with other women.