"Origin: Japan. An evil demon that can read people's minds. Also known as Ama no Sakugami, it reads minds, then says/does the opposite. It is also said to eat humans from the inside, then becoming them by wearing their skin."
—Shin Megami Tensei A-Mode DDS Dictionary
Amanojaku appears in Shin Megami Tensei as the second boss when he eats and impersonates the protagonist's mother, after gaining entry by impersonating a policeman asking about the protagonist.
Amanojaku is a boss in Ice Book, faced in Akuma no Hokora. He's assaulting his fellow demon Mecchii for being a pacifist and not wanting to take part in attacking the Devil Children. He attacks upon seeing Akira, but loses the battle and dies shocked at the strength of an Devil Child.
Amanojaku flees from the village in Fire Makai due to an attack by Imperium demons. After Jin beats them, the demon returns after the battle to give his thanks for saving his friend Nemea. On Akira's route an Amanojaku is trapped inside a snowman, which Amy Kashihara kicks and releases him. He flees once he sees Imperium soldiers nearby.