Killer Bee basically gave a shit load of chakra before getting serious a bit(i say a bit for a reason). Goes V2 and puts a HOLE Through kisame's chess with sword in hand!
The whole fight he had to hold back because he had his friends to worry about (FACT OF THE MANGA)
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Then he almost kills him with just V2, Which kisame admits he cannot absorb all his chakra.
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Then even when kisame made shark bubble dome, he still had to protect his friends before fighting (fact) and by that time all his chakra was basically gone. It was because of his friends he had to protect was because he couldnt get serious FACT!
If he would have hit him with a tailed beast bomb Im 10000% it would had killed Kisame. Especially since Kisame couldnt handle V2 and samahadra complained from a fire ball jutsu that isnt halve the power and desrtuction of TBB
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