In Kingdom Hearts you find a Legend on the computer in the World's Prison at the End Of The World.

Ones born of the heart and
darkness, devoid of hearts,
ravage all worlds and
bring destruction.

Sieze all hearts
and consummate the great heart.
All hearts to be one,
one heart to encompass all.

Realize the destiny:
the realm of Kingdom hearts.
The great darkness sealed
within the great heart.

Progeny of darkness, come
back to the eternal darkness.

For the heart of light
shall unseal the path.

Seven hearts, One Keyhole,
one key to the door.

the door of darkness,
tied by two keys.

the door of darkness to
seal the light.

None shall pass but shadows,
returning to the darkness.

Ones born of the heart
and darkness, hunger
for every heart until
the dark door opens.