Shizune is an elite jōnin and medical-nin from Konohagakure, the niece of famed shinobi Dan Katō. After her uncle's death, she accompanied his lover, Tsunade, leaving Konoha to become Tsunade's first apprentice and devoted attendant. This forged a lifelong bond where Shizune consistently prioritizes Tsunade's welfare. During their travels, she managed Tsunade's affairs, frequently expressing concern over Tsunade's gambling debts and defending Tsunade's emotional state, such as after performing surgery on a Fourth Raikage comrade. Upon Tsunade's appointment as Fifth Hokage, Shizune returned to Konoha as Hokage's Assistant, retaining the role under Sixth Hokage Kakashi Hatake and Seventh Hokage Naruto Uzumaki. She also serves as a doctor at Konoha Hospital. Shizune exhibits a level-headed, practical, and rational nature, often worrying over details and Tsunade's impulsive choices. Her fierce loyalty leads her to object to actions she deems unethical, like opposing a potential alliance with Orochimaru (believing Dan and Nawaki wouldn't want resurrection at the cost of innocent lives) or alerting the Konoha Council to a mission she considered too perilous for Naruto. She cares for Tsunade's pet pig, Tonton, and avoids pork products, occasionally displaying insecurities about her personal life and appearance compared to other kunoichi. Trained by Tsunade, Shizune's medical ninjutsu is surpassed only by Tsunade and Sakura Haruno. Her exceptional chakra control enables complex procedures like cellular regeneration and leadership of Konoha's medical teams, such as healing Neji Hyūga after the Sasuke Retrieval Mission. In combat, she specializes in poison-based techniques, exhaling lethal fog and deploying poison-coated senbon or kunai via wrist devices or orally. She also demonstrated proficiency in the Shadow Clone Technique and fūinjutsu, leading the Three-Tails sealing mission. Her analytical skills allowed her to decipher the function of Pain's chakra receivers via autopsy and identify genetic links between the White Zetsu Army and Hashirama Senju during the Fourth Shinobi World War, where she commanded the Allied Shinobi Forces' Logistical Support and Medical Division. Key involvements include confronting Kabuto Yakushi during Orochimaru's recruitment attempt on Tsunade; being captured by Pain's Human Path, which extracted Naruto's location before killing her (later resurrected); mentoring Sakura in the Boruto era; treating injured characters like Mitsuki and Boruto Uzumaki; and subtly navigating Sarada Uchiha's questions about parentage during Sakura's illness. Shizune's birthdate is November 18, her favorite phrase "The flowers, the birds, the wind, and the Moon," and her mission record totals 139 missions (3 A-rank). Her attire includes a bluish-black kimono during peacetime, a standard flak jacket for missions, and a one-sleeved black kimono with mesh armor post-war.