Persona 5: The Animation - Season 1 Episode 17 -

Ren and the others convince Futaba to open the door to her room of her own free will. Then the Phantom Thieves sneak back into the Palace to steal Futaba's Treasure, but she follows them, becoming the first case of someone entering their own Palace. Inside, Futaba encounters a giant monster in her mother's form with a deep grudge against Futaba.