Sorry for ignorance, but it says futa/trans, but not protagonist. The protag is a futa, or the tag is simply mentioning the game has that content?
		
		
	 
From game intro:
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Japan, mid-21st century.  The psychic energies of humanity have finally begun to coalesce into physical form.  The resulting beings are known as Demons.  Born from the base desires suppressed deep within the human mind, these creatures spread across the planet, leaving chaos and depravity in their wake.
But Demons do not represent the entirety of the human condition.  The hopes and determination of humanity have also risen up, gathering in the bodies of a few Chosen warriors in order to grant them the power to fight the Demons.  Although each of them was once an ordinary person, their new abilities place them at the center of the struggle for the soul of humanity.
You are a Demon Lord, the highest form of Demon, with your own mind and will, focused on the corruption of all that is good in the world.  The Chosen are the keystone of humanity's resistance to your goal, but to simply kill them would be meaningless.  Instead, shatter their notions of right and wrong, showing them the true darkness that hides within!
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I think most of the time the form the Demon Lord takes isn't described, outside of battle or some scenes. Your Demon Lord can be thought of as an intelligent malevolent shadowy presence for most of the actions described in the game. But at various points, some incarnate forms are useful, like:
- fuckzilla
 
- a many-mouthed, many-tongued gibbering laughing floating head spouting insanities
 
- a cyborg hacker who can proficiently wield its own wires as combat whips, while taking over world communication platforms
 
- big dude with big dick built for fuckin'
 
- a sentient vat of of acid, both the psychedelic kind and the dissolving kind, simultaneously
 
- the costumes of the magical girls themselves
 
- futa, if you want
 
I would say that if you're in the mood to play a singular character with a fixed appearance there are probably other games that better fit that style of play.