Kisame is Itachi's partner, replacing Orochimaru. His specialty is the use of water jutsu and also uses his trademark sword, the Samehada, which only he can yield.
Although we always view Kisame Hoshikagi to be some grotesque monster that was born a tragedy and ate his own kind, it wasn't always so. Before he became the notorious rouge ninja with an appetite for swordplay, he was a member of the secret intelligence squad. He was born and raised by the previous owner of Samehada and he also killed him. Although we don't get his name, we do know what he looks like and it was very similar to the way that Kisame looks. He resembles some sort of shark but he's more stoat.
During a secret mission, his ninja-team are caught by Ibiki Morino, the hidden leaf village's notoriously famous torture specialist and so, he kills his team-mates so no information is leaked. For his loyalty, he is approached by the fourth Mizukage and Kisame explains that it was not bravery or loyalty but a "living lie." It turns out that the fourth Mizukage was being controlled by Uchiha Madara and he explains to Kisame the 'eye of moon plan' to destroy the world. Although Kisame thought this was crazy, he wanted to see the world for what it was and joined Akatsuki.
Kisame Hoshigaki makes his first appearance in the series alongside Itachi Uchiha during the search for Tsunade arc. Hatake Kakashi spots them and sends Asuma and Kurenai to confront them. They do so and are both over-powered by the black-robed duo. Kisame is shown to be an aggressive fighter and only stops when Itachi tells him to. This is the first time we meet Akatsuki members and it's when we first hear about their true intentions to capture Naruto and the rest of the tailed beasts.
Kisame and Itachi escape and find Naruto alongside Jiraya, but can't quite say that there strength could match up and so the two are separated and Naruto is left to fend for himself. Itachi and Kisame confront him and before they can take off his arms, Jiraya returns to fight them off. Sasuke Uchiha arrives and has a fight with Itachi but is trounced and left for dead. Jiraya uses a jutsu that should trap and kill the two, but Itachi uses ameterasu and bursts out.
Rescue the Kazekage arc
While Akatsuki are taking the tailed beast out of Gaara, they can see that Team Guy is heading towards their position. Kisame - remembering his previous encounter with Might Gai - volunteers to stop the intruders. Pain creates a clone for Kisame to control and he sends it out to fight him. After a long fight, the clone is defeated. Gai was pushed to open the sixth gate and after the clone was defeated, Kisame regretted to tell Itachi that the clones only had 30% of their total chakra.
Itachi Persuit arc
After an unseen fight, Kisame defeats the four tails without a scratch. Kisame and Itachi are then confronted by Sasuke Uchiha and his team-mates. While Sasuke Uchiha fights Itachi, Kisame must fight his old pupils brother Siegetsu.
Invasion of Pain arc
Upon the death of Itachi, Madara apologises to Kisame about Itachi and reveals his true identity. Kisame feels better knowing it was he that was pulling the strings.
Five Kage Summet arc
After Sasuke Uchiha was, "fooled" by the eight tails it was Kisame's job to capture him. Kisame uses Samehada's chakra abilities to seek him out, which he does so successfully. In the midst of the battle, the eight tails brother and Raikage beheads Kisame who dies smiling. The eight tails picks up Samehada and takes him as his own. It is later revealed that the eight tails was fighting a clone that Zetsu made and that Kisame was hiding in Samehada.
Confining the Jinchuriki arc
Kisame breaks out of Samehade and attempts to flee, but it fought by Might Gai once again. After a long and heated battle, Kisame uses a water prison jutsu on himself and before he was drained of chakra, he summoned three sharks to eat him and his secrets alive. In his final seconds of life, he realized he was not as terrible as he once thought, as he gave his life for something he believed in. In his final moments he also sent his location to Zetsu which would lead Madara to Naruto and the eight tails.