Seriously, Gai Sensei kick ass! If Naruto isn't the main lead, they should change the title to "The Super Hot-Blooded Ninja Sensei" With a ridiculous attack called Afternoon Tiger, Gai can take on any evil ninjas! Of course, the focus was Kisame's past where he killed his own comrades to guard their secrets. That is the order of the previous Mizukage which Madara is controlling him.
Most probably, Kisame will meet his demise in one or two chapters. Let see how it goes..