Shizune is a kunoichi of Konohagakure. An apprentice of the legendary Sannin Tsunade, Shizune became a talented medical-nin under her tutelage; also becoming her companion during her sabbatical from active shinobi duty. After Tsunade is persuaded to return to Konoha to become its Fifth Hokage, Shizune assumes the role of her assistant — a role she would retain long after Tsunade retired from the post, performing the same duties for the Sixth and Seventh Hokage.
Shizune is the niece of Dan Katō, a renowned shinobi of Konoha. Some time after her uncle's death, Tsunade, his lover, left Konoha and Shizune went with Tsunade as her attendant and apprentice. The bond between Tsunade and Shizune is strong and, above all, the latter sees her purpose in life as caring for Tsunade.
During their time away from the village, Shizune often worried about Tsunade's constant gambling, losing money and then borrowing more. In the anime, on one such occasion when they were at a gambling den, they were approached by the Fourth Raikage and Amai who beseeched Tsunade to help their injured comrade. After Tsunade complied, Shizune was actually the one to conduct the surgery, and when she told the Raikage of her master's two great losses, upon hearing his response that her master was unhinged, she chided the Raikage, throwing the Exploding Insect. Recomposing herself, she told Amai, who had been aiding in the surgery, to finish up.
Shizune is always level-headed, practical and a rational thinker. As a result, she is the one who tends to stress over details, such as Tsunade's tendency to gamble frequently, and to think with her heart. She often gets comically worked up over any irrational decision Tsunade makes. Shizune also looks after Tonton, Tsunade's pet pig. She is a very kind and calm person but will immediately rush to Tsunade's aid and in contrast, will become fierce and somewhat ruthless; a testament of her loyalty to Tsunade, including losing her temper when anyone insults her. At the same time however, she is not timid and is not afraid of objecting to Tsunade's decisions or voicing her opinion as seen when she even alerted the Konoha Council to Tsunade's intention to send Naruto on a mission that Shizune thought would put him in great peril. She has a great sense of morale and ethics, as she tried to persuade Tsunade from accepting Orochimaru's offer to heal his arms in exchange of reviving Dan and Nawaki, believing the said two would not be happy to return at the cost of innocent lives.
She is not the type to tire easily and is very energetic and efficient while acting in her capacity of Hokage's Assistant, often urging Tsunade to finish the paperwork in order to avoid mountains of unsigned documents later on. She is often seen asking Tsunade questions about what to do with the village and the shinobi on missions. In an omake, she has shown she is a bit jealous of kunoichi like Tsunade and Kurenai Yūhi, complaining about their assets compared to her own.
Shizune is a fair-skinned woman of average height and slender build with onyx eyes and jet-black hair; her hair is straight and shoulder-length with bangs that cover her ears and frame her face. Normally, Shizune is seen in a long bluish-black kimono with white trimmings, held closed by a white obi, and open-toed sandals with low heels. Shizune has also been seen wearing the standard Konoha shinobi outfit complete with flak jacket, when deployed on missions which has distinct, extra-long sleeves. She, however, doesn't wear a forehead protector. Shizune also has the tendency to pin her hair up when working; a trait also shared by Sakura.
During the Fourth Shinobi World War, she donned her standard shinobi attire, albeit with shorter sleeves this time. She also wore the forehead protector of the Allied Shinobi Forces and a band around her right arm signifying her position.
Years after the war, Shizune had gained vaguely noticeable creases around her eyes. She wears a black, one-sleeved kimono held closed with a with a sash. Beneath this, she wears mesh armour, which is partially exposed on her sleeveless left-hand-side.
As a jōnin and apprentice of Tsunade, Shizune is undoubtedly a very capable kunoichi. Jiraiya had enough faith in her abilities to leave her to fight Orochimaru's right-hand man, Kabuto Yakushi. A further testament to her credibility is being put in charge of the Logistical Support and Medical Division of the Allied Shinobi Forces during the Fourth Shinobi World War.
In the anime, she could perform the Shadow Clone Technique, able to create at least 36 clones at once. She also demonstrated capabilities in fūinjutsu, able to lead her team in the process of sealing the Three-Tails.
Shizune is a very talented medical-nin. Her prowess set a high standard for Tsunade's other disciple, as she stated that she had not seen such skill when comparing Sakura Uchiha to her. Shizune's refined chakra control allowed her to perform even the most complex medical ninjutsu, such as leading a team in regenerating a person's injured body with new cells; a task that took over three hours to complete, while the slightest mistake could be fatal.
Poison Techniques and Weaponry
Shizune's main tactic in battle involves incorporating poison into her attacks. She can emit poisonous gas from her mouth, capable of being fatal if even a whiff of it is inhaled, as noted by Kabuto in the anime. Shizune also imbues her senbon with poison, and kunai as well. She can either fire senbon from a concealed wrist-mounted device, or from her mouth in quick succession.
Shizune is quite observant and has a keen intellect. She was able to figure out the secret behind the black receivers embedded in Pain's First Animal Path during an autopsy with her team after just a short amount of time. Likewise, during the Fourth Shinobi World War, she could find out the DNA-similarities between the White Zetsu Army and the First Hokage, something that she already presumed before.
Shizune appears in this arc.
Sarada Uchiha Arc
Shizune takes care of her fellow disciple, Sakura Uchiha, after Sakura fainted and sent Shizune by Sakura's daughter, Sarada. Shizune told Sarada that her mother has fainted many times before. When she later talked to Sarada, who was looking at a photo of her father with team Taka, the girl talked about her doubts on her parentage. Shizune insisted her doubts were false. When Sarada called her on it, noting that she knew there were no records of her birth. Shizune merely kept quiet with a sorrowful expression on her face. She questions Sarada to why she brought this on, to which Sarada showed her the picture of Taka and particularly Karin and how she wore the same glasses as her.
Later, while discussing Naruto and Shikamaru preparations for the upcoming Academy graduations, a letter was received from Sasuke, learning of a young boy with the Sharingan attacking the Uchiha. While Naruto decided to go handle things personally while leaving a shadow clone behind, Shizune was concerned on how this would conflict with the graduation exams. Later, as Sakura finally recovered, Shizune explained to her of Sarada's recent actions of going after her father.
- (To Tsunade) "Lady Tsunade! You can't!! Don't listen to the offers of these liars. Your brother and my uncle wouldn't want you to do this either!!"
- (To Tsunade) "Are the wishes of two people more... Tsunade!! Your dreams... your wishes... Have you forgotten them?"
- (To Naruto) "You may think you're all healed, you may even look all healed, but you're NOT all Healed!"
- (To Naruto) "All in good time, just as soon as you're completely healed."