Kaido is a ruthless and confident warrior who tried to prevent the Great War by confronting Edward Newgate before the latter attempted to save Portgas D. Ace from execution. He apparently craves excitement, as he threatened to start the biggest war the world has ever known.
Kaido is unforgiving and intolerant and is not open to negotiations or excuses, which makes it seem reckless to provoke or underestimate him. He is the captain of the beast pirates and a man with a 4.6 billion berry bounty.