The Pure Hearts are 8 sacred hearts created by the Tribe of Ancients that hold great power in them. They are able to counter and destroy the Chaos Heart.
When Count Bleck is revealed to have obtained the Chaos Heart, the heroes hear of the Pure Hearts and set out to collect them. 2 are collected by the heroes, 5 are given by High Max. When Count Bleck arrives to obtain the 7 hearts, High Max appears with the last one. Using the power of the 8, he destroys the Chaos Heart Count Bleck has fused with and easily defeats him. He infuses the power of the hearts into Mega, Talia, and Starman, 2 each, and fuses with the final 2 hearts.