Tsubaki Shikibe is the younger sister of Ibuki and Mizuki Shikibe, making her Yuki Giou's maternal aunt. Her childhood was intertwined with Senshiro Furouri and Garan due to a long-standing family arrangement betrothing her to Senshiro. This engagement dissolved when Senshiro prioritized his duties as Kuroto's Zweilt partner, a choice Tsubaki supported despite deep personal sadness. Senshiro remains one of the few men she does not hate; she blushes shyly when he smiles at her, indicating lingering feelings, though he treats her platonically. Serving as one of the Giou Clan's "Masters," Tsubaki instructs Zweilt members and others in martial arts and combat at a training dojo. Her apprentice is the necromancer-in-training Masamune Shinmei, whom she frequently berates for comedic effect within their core mentorship. Tsubaki possesses a loud, expressive, and emotionally open personality, contrasting sharply with her elder sister Ibuki's calmness. She openly critiques others' flaws and talks back, even to figures like Takashiro Giou, though less intensely than with Masamune. While she declares a general hatred for men, she makes exceptions for Yuki and Senshiro. She is deeply doting towards her nephew Yuki, displaying overt affection upon their first meeting by hugging and attempting to kiss him, leading others like Tachibana to label her an overly devoted aunt. When Yuki learned the truth about his birth, Tsubaki tearfully hugged him and apologized for the secrecy, explaining she and Ibuki were bound by Takashiro's orders. Her relationship with Kuroto Hourai is hostile, originating from a contentious childhood first meeting due to Kuroto's rudeness. They clashed frequently afterward, often requiring Senshiro's mediation. Tsubaki challenged Kuroto to a shoji match after his rapid rise in rank but lost effortlessly, fueling her resentment. With Garan, she shares an affectionate, grandparent-like bond; he treated her as a granddaughter and offered guidance, particularly when she misunderstood Kuroto's behavior. Her name "Tsubaki" (椿姫) combines "camellia flower" (椿) and "princess" (姫).