Emkay's song comes from king dice i just noticed, where he sings that he is the devil's right hand man : r/EmKay

CupHead OST - Die House (King Dice) (with Lyrics)

How I met king dice and the devil (part 1)

How I met king dice and the devil (part 1)

The Cuphead Show King Dice & The Devil

The Cuphead Show King Dice & The Devil

The Nightmare Before Christmas Part 15 - King Dice's Song

The Cuphead Show King Dice & The Devil

Devil's In The Details - ORIGINAL CUPHEAD JAZZ SONG by RecD

Devil's In The Details - ORIGINAL CUPHEAD JAZZ SONG by RecD

How I met king dice and the devil (part 1)

On A Roll - ORIGINAL CUPHEAD SWING SONG ft. King Dice & Devil by

The Nightmare Before Christmas Part 15 - King Dice's Song