Kakashi Hatake, a highly skilled ninja from Konohagakure's Hatake clan, was born to Sakumo Hatake, a renowned shinobi known as "Konoha's White Fang." Early trauma struck when his father committed suicide after facing vilification for prioritizing teammates over mission success, leading Kakashi to strictly adhere to shinobi rules during his youth. A prodigy, he graduated from the ninja academy at five and became a chūnin by six. Assigned to Team Minato under Minato Namikaze alongside Rin Nohara and Obito Uchiha, he fought in the Third Shinobi World War. During a mission to destroy Kannabi Bridge, Obito sacrificed himself to save Kakashi, gifting his left Sharingan eye to replace one Kakashi lost in combat. This earned Kakashi the monikers "Copy Ninja Kakashi" and "Kakashi of the Sharingan" for using the eye to copy over a thousand jutsu. The later death of Rin—killed by Kakashi to prevent the Three-Tails sealed within her from destroying Konoha—activated his Mangekyō Sharingan and inflicted lasting emotional trauma.

As a jōnin, Kakashi captained the Anbu before leading Team 7, consisting of Naruto Uzumaki, Sasuke Uchiha, and Sakura Haruno. His teaching philosophy emphasized teamwork over rule adherence, influenced by Obito's sacrifice, and he tested students through bell trials requiring cooperation. In the OVA "Battle at Hidden Falls. I Am the Hero!" (alternatively titled "The Lost Story - Mission: Protect the Waterfall Village"), Team 7 escorted Takigakure leader Shibuki home. After arrival, Kakashi departed for Konoha, leaving his students to independently defend the village against rogue ninjas led by Suien, who sought the power-enhancing "Hero Water." Naruto, Sasuke, and Sakura repelled the attack without Kakashi's direct involvement, demonstrating his teachings on self-reliance and teamwork. His role concluded after the initial escort.

Kakashi developed signature techniques like Chidori ("One Thousand Birds") and its refined Lightning Cutter, both requiring the Sharingan's precision for safe use. After losing the Sharingan in the Fourth Shinobi World War, he created the ranged Purple Electricity. His Mangekyō Sharingan granted access to Kamui, a space-time jutsu warping targets to another dimension. Temporarily gaining dual Mangekyō Sharingan from Obito Uchiha enabled him to manifest Susano'o and wield Kamui Lightning Cutter. Post-war, he served as Sixth Hokage without an active Sharingan. In retirement, he advised former students and allied villages. His legacy endures through generations of shinobi mentored in his ideals of protecting comrades and village.