The character first appeared in Metal Gear Solid, using his psychic power to remind minds and players’ memory cards.
And fans think they can see the character in the new Death Stranding trailer:
Of course, Kojima doesn’t make Metal Gear games anymore and does not own the character Psycho Mantis (Konami does), so this probably isn’t actually Psycho Mantis. But considering how the character was previously used to break the fourth wall, maybe it’s a nod to Kojima’s previous work? Or maybe it’s just another time Kojima has gotten in fans’ heads?