Pisacas are demonic creatures that feast on human meat, especially corpses. They are mentioned on the same level as other abominations as Rakshasa and are considered to be the physical incarnation of ignis fatuus. The origin of their names is believed to have been a result of the demonization of Hindu tribes by Aryan people.
They like darkness and haunt cremation grounds along with other demons like Bhutas (meaning ghosts) and Vetalas. Pisacas have the power to assume different forms at will, and may also become invisible. Sometimes, they possess human beings, and the victims are afflicted with a variety of maladies and abnormalities like insanity. Certain mantras are supposed to cure such afflicted persons, and drive away the Pisaca which may be possessing that particular human being. In order to keep the Pisacas away, they are given their share of offerings during certain religious functions and festivals.
"Origin: India. A type of Hindi preta that eats human bodies. They are dirty, ugly demons that appear at crematories after dusk. They can suck the life out of living beings and plants, and can curse humans to death. Those possessed by Pisaca eat the flesh of the dead."
—Shin Megami Tensei A-Mode DDS Dictionary
Pisaca is one of four demons Gotou summons before facing the protagonist himself.
"A type of demon in Hindu mythology that arises from the vices of men such as criminals, drunkards, and adulterers. It enters through an opening in the body and influences its host's actions."
—Shin Megami Tensei III: Nocturne compendium
Pisaca can be encountered in the Kabukicho Prison, although the Demi-Fiend cannot speak to them unless he either uses the Jive Talk conversation skill if he has it or encounters one in a dazed demon state during the Full Kagutsuchi.
A Pisaca with exploration skills can be purchased from a Shady Broker in the Labyrinth of Amala's First Kalpa for 15,000 Macca.
Pisaca can be contracted on Ichigaya field, in Ichigaya Camp's silver-level instance, and the Old Tokyo Metro. Pisaca appears as a mini-boss on B11 of Ichigaya Camp's gold-level instance and alongside of Komokuten when he is summoned to the boss room. They appear as a minor field boss in Ueno, as part of the invasion forces in Shinagawa during the weekend, as support for the Vetala boss of the Old Tokyo Metro instance, and as one of the demons contracted by the punks in Ikebukuro.
"A type of preta in Hindu lore that eats human corpses. It enters a human through the mouth and causes harm to its host until expelled. Those who see one are said to die within nine months."
—Shin Megami Tensei IV Apocalypse compendium
Pisaca can be found in Ikebukuro. It can teach Nanashi the Bind Voice, Life Drain, Mudoon, Tarukaja and Acid Breath skills through its Demon Whisper. It benefits from learning ailment, Force, Darkness and support skills.