Kakuzu was much older than he appeared, having been one dispatched by his village to assassinate Shodai Hokage. Unfortunately Shodai's Mokuton got the better of Kakuzu, and he returned having failed in his mission. Dispite the challenging nature of his mission, he was stigmatized and punished by his village for the failure. After escaping his imprisonment, he took and used the village's ultimate Kinjutsu Jiongu, which extended his life by withdrawing the hearts of his opponents. He made use of this ability by taking the hearts of the village leaders and leaving his former comrades behind.
Jiongu also allowed him to utilize the chakra nature of the original heart removal victim, granting him access to all five chakra elements. Kakuzu's body was held together by the mysterious black Jiongu tendrils, which sewed together various chunks of his body. These stitches could be removed to allowed him to extend his body parts. After leaving the village Kakuzu partnered with many ninja, usually killing them out of dislike. He eventually joined Akatsuk and partnered with another "immortal" named Hidan. Hidan and Kakuzu were directed to capture the two-tailed bijuu Jinchuuriki Ni'i Yugito. This kunoichi from Hidden Cloud was highly skilled and not easily captured by the pair. The Jinchuuriki seemed to have been assigned as Kakuzu's personally to capture.
After handing off Yugito to Zetsu, Hidan and Kakuzu headed to the Fire Country Temple in search of a bounty head. There Kakuzu and his partner wiped out many of the monks and killed Chiriku, Kakuzu's bounty target. The two men then headed to a bounty station to cash in Chiriku. After receiving his money Hidan and Kakuzu were attacked by a team from Konoha. In the battle, Hidan killed Sarutobi Asuma and the two men were forced to withdraw after being contacted by the Akatsuki leader. They assisted in the withdrawing of the Nibi from Yugito and then sealing it and the Sanbi in the King of Hell Statue.
On their journey to find their second Jinchuuriki, they were stopped by Team 10 and Kakashi. The team was set on revenge for Asuma's death. Shikamaru led Hidan off to fight alone and Chouji, Ino and Kakashi began to battle Kakuzu. Seeing Kakuzu use a Earth element jutsu to harden his body, Kakashi quickly moved to pierce Kakuzu's heart with Raikiri, as Lightning beat Earth. Kakuzu wasn't dead though. He removed his cloak revealing four tendril entities. These entities wore masks and contained the hearts of opponents he had fought. The Earth entity was killed and he began to attack using his other masks. Chouji managed to damage the Lightning mask and Hidan unfortunately damaged Kakuzu's original Water heart with his jutsu.
Kakuzu was forced to absorb the Lightning heart to live and he moved to unleash more Fire and Wind attacks. Naruto and Team 7 arrived to assist and Naruto asked to take on Kakuzu alone, to prove his growth. He moved to attack with his new Fuuton Rasen Shuriken, but it failed. He then tried again, using a clone diversion wielding Rasen Shuriken as well to get access to Kakuzu's blindside. The attack struck home, destroying Kakuzu's hearts and critically wounding him in a maelstrom of destruction. Kakuzu couldn't believe such young people had beaten him and Kakashi told him that to one who fought Shodai, they would be kids. But now Kakuzu was just a beaten old man. Kakashi then finished Kakuzu off with a Raikiri. Kakuzu's body was then taken back to Konoha for autopsy. Tsunade examined his cells to determine the extent of the damage Naruto's new jutsu caused. It is unknown what happened to Kakuzu's body after the examination but Konoha still appears to have held on to it and his ring.
- Earth Grudge
- Earth Style: Iron Skin
- Fire Style: Searing Migraine
- Lightning Style: False Darkness
- Water Clone Jutsu
- Water Style: Hiding in Water Technique
- Wind Style: Pressure Damage
He has some kind of Jutsu that hardens his body!
Shikamaru: He has some kind of Jutsu that hardens his body!
Kakuzu: Good eye.