Despair difficulty...
	Hard Mode...
	Memnon...
	New Gladiator skins...
	Nightmare Mode...

Finish game in Nightmare difficulty.

Beat game on the Normal Difficulty.

Clear Despair Mode once.

Beat the game once. Load complete game save. In the character creation(Body type) screen you will find that there are more skins than the default 4 skins.

Beat game on the Hard Difficulty.