A kunoichi of Konohagakure, Shizune is introduced as the niece of Dan Katō and Tsunade's devoted apprentice. After Dan's death, she accompanied Tsunade during her prolonged absence from the village, serving as both attendant and medical protégé. Their bond centers on profound loyalty, with Shizune prioritizing Tsunade's welfare while frequently mitigating consequences of Tsunade's gambling tendencies. Shizune blends level-headed pragmatism with deep ethical conviction, often acting as a rational counterbalance to Tsunade's impulsive choices. She voices concern over financial risks or moral compromises, notably opposing Tsunade's potential alliance with Orochimaru by arguing that resurrecting Dan and Nawaki through harmful means would betray their values. Her strong morals extend to professional contexts, from objecting to risky missions for Naruto Uzumaki to condemning unethical medical practices. Despite her calm exterior, she exhibits fierce protectiveness when Tsunade faces threats, and comedic moments stem from her exaggerated reactions to stress or romantic insecurities. She cares for Tsunade's pet pig Tonton and avoids pork products. Shizune has fair skin, black eyes, and shoulder-length black hair typically pinned up during work. Her standard attire includes a bluish-black kimono with white trimmings and a white obi, though she dons Konoha's shinobi gear with elongated sleeves for missions, usually without a forehead protector. During the Fourth Shinobi World War, she wore modified shinobi attire featuring the Allied Forces' forehead protector and a medical division armband. In the Boruto era, she sports a black one-sleeved kimono with mesh armor underneath, showing subtle age-related changes. As a jōnin and Tsunade's first apprentice, Shizune masters medical ninjutsu and poison-based combat. Refined chakra control enables complex procedures like cellular regeneration and leading the Three-Tails sealing operation. She employs poison gas emitted orally and toxin-coated senbon or kunai delivered via wrist devices or mouth projection. Her tactical intelligence surfaces in rapid analyses of Pain's black receivers and White Zetsu's DNA link to Hashirama Senju. Databooks confirm her use of Shadow Clone Technique, Mystical Palm Technique, and Poison Mist Ninjutsu. Key involvements include clashing with Kabuto Yakushi during the Search for Tsunade Arc to prevent Tsunade's collaboration with Orochimaru, later aiding Tsunade and Naruto. In Part I, she healed Genma Shiranui and Raidō Namiashi post-Konoha Crush, managed Chunin Exams coordination with Sunagakure, and led Neji Hyūga's cell-regeneration surgery. Following Jiraiya's death in Pain's Assault, she autopsied the Animal Path, uncovered the black receivers' function, was killed by the Human Path, and revived via Outer Path: Samsara of Heaven. During the Fourth Shinobi World War, as captain of the Allied Forces' Logistical Support and Medical Division, she organized field medicine, directed White Zetsu autopsies, and coordinated mass healing with Katsuyu against the Ten-Tails. In the Boruto era, serving as the Seventh Hokage's assistant and Konoha Hospital doctor, she cared for Sakura Haruno post-collapse, discussed Sasuke Uchiha with Sarada Uchiha while withholding birth-record details, provided Naruto with fatigue medicine, oversaw Mitsuki's emergency treatment after the Momoshiki invasion, healed Boruto Uzumaki following Team 7's battle with Deepa, and attended Fourth Shinobi World War memorial services. Her trivia notes a November 18 birthday, preference for cooked brown rice, avoidance of pork, and the favored phrase "the flowers, the birds, the wind, and the moon." Her mission record comprises 74 D-rank, 44 C-rank, 18 B-rank, and 3 A-rank missions, with no S-rank completions.