Unknown Specimen 5, referred to as Lisa in the game files, is one of the new specimens encountered in the Endless Mode.
Lisa resembles a woman with gray skin, long brown hair, and a tattered, dirty beige dress. Her head droops toward her left shoulder as if her neck is broken and her face is frozen in a wide grin. One eye seems to be missing while the other is dead white. Her arms hang stiffly down at her sides and her bare legs and feet seem to be swollen. While moving, her body stays rigid while her head and neck contort violently in many directions.
During her game over screen, a close up of her face is shown with a centipede crawling out of her eye and various other bugs coming out of her mouth. This also reveals that several of her teeth are missing.
The first sign of Lisa's presence is that the ambient sounds that usually play inside the mansion will go silent. As the Protagonist moves from room to room, the screen will gradually become tinted in deep red. Occasionally, the slime variant of Specimen 1 (with its paint fading) will silently pop out of the sides of walls, always bearing a note. These notes are brief and ominous.
As the Protagonist walks through more rooms, the screen will become redder. Alongside a deep, guttural ambiance. A few rooms later, Lisa will appear and begin chasing the player character.
She enters through the door of each room and will slowly float towards the Protagonist. They must keep her in their sights, otherwise, she will immediately appear behind them and attack for a moderate amount of damage. Keep in mind that she can still move when in the player's vision.
Every time she attacks the Protagonist, she teleports to a random place around them. Eventually, the room number will start looping until the Protagonist has escaped her. If she kills the player character, an image of her rotting face will flash onto the screen with this message:
"You cannot dream without darkness.
"You cannot wake without pain.
"Tear off your foolish disguise.
"I've been watching you for some time now."
"Why even bother filling your lungs?"
"Reading these won't help you. Only death can help you."
"You think you're clever don't you?"
"Do you feel safe?"
"Your blood smells so thick. I can hear the vessels oozing."
The ambience that plays before Lisa starts chasing the player.
"LISA AMB2", Unknown Specimen 5's chase theme.
- She is based on the character of the same name from the short horror game P.T. The rooms becoming red and looping endlessly during the chase also mirror the nature of said game.
- Unknown Specimen 5, along with Unknown Specimen 1, are the only enemies who can temporarily stop the room counter from increasing.