Tsurara Amatsuka, the sixth daughter in the nineteen-sister Amatsuka family, is a 13-year-old second-year junior high student. She possesses hip-length silver or blue hair typically styled in twintails with ribbons, along with red or purple eyes, and stands 155 cm tall. Born March 14 (Pisces) with blood type O, her personality features a short temper and initial hostility toward Yōtarō, the family's newly adopted brother. She openly rejects him, labeling him a "manservant" and criticizing his presence. Displaying classic tsundere traits, she reacts to Yōtarō's accidental offenses with physical aggression like hitting. She harbors insecurity about her small bust size, often comparing herself unfavorably to her younger 12-year-old sister Rikka, whose larger bra size heightens Tsurara's irritability regarding body image or Yōtarō's proximity. Her development surfaces during a family riverside trip. Though she slaps Yōtarō for perceived misconduct early on, she later shows reluctant gratitude when he compliments her swimsuit, delivered tsunderely. A pivotal moment occurs as she and youngest sister Watayuki drift toward a waterfall on a raft; Yōtarō and sister Mizore rescue them, though Tsurara never acknowledges it. Tensions escalate when she discovers Yōtarō in the mixed-gender family hot spring. To prevent him seeing her or her sisters unclothed, she forces him underwater. His struggle for air causes accidental physical contact with Tsurara and Hikaru, provoking embarrassment and another beating. Later, during a private conversation, Tsurara and Yōtarō share an unexpected kiss, witnessed by Mizore. Tsurara flees in intense embarrassment. Despite this, her attitude subtly shifts from overt rejection to a conflicted, though still tsundere, acceptance of Yōtarō’s familial role.