The first appearance of the Lost Hero is on the Version 12 or Evo 5, that strongest shark Cobalt ( In Japanese ) or Brutus in English. It has trendemous strength, it also have some skills which really amazing, making it a Lost Hero. The colour of that shark is blue, it is the brother of Master Blue. This should be revealant, this shark can revive itself after health reaches zero ( 'Summon the Grim Reaper' Effect ), works more better with Survivor!
This animal led the 3 animals ( In Japanese ) and 5 animals in English Version ( Evo 5 ) got out of their prison, which make them an Escaped Animals or Villain Beasts ( Joker, Shuffle, Ace, Spade, Straight ), and Cobalt or Brutus himself is the boss animal of V12 ( Evo 5 ), while the card has been released at that version too.