Kyuuyaku Megami Tensei

Megami Tensei: Akemi Nakajima, a programming genius, invented a Devil Summoning Program. But after gaining physical bodies, the demons Loki and Set attacked the summoner. He was saved by a mysterious transfer student, Yumiko Shirasagi. Nakajima and the magic-wielding Yumiko joined forces and repelled the demons... However... The demons have not surrendered. Lucifer, a once beautiful angel who was cast into Hell, is planning to conquer the human world! A demonic palace has appeared in Asuka... where the tomb of the goddess Izanami rests under Shirasagi Mound. The powerful Izanami has been captured by Lucifer, and her chamber sealed within the palace. To save Izanami... defeat the resurrected Loki and Set, and Lucifer himself, Nakajima and Yumiko walk through the palace's entrance... But will they ever be able to return to the surface...?

Megami Tensei II: In the year 199X, the world was demolished with a bombardment of missiles, and the survivors of the cataclysm were forced to live in shelters. It's now the year 2036, and two friends are playing a video game called 'Devil Busters' in the Keihin shelter No. 3. Shortly after they beat the first boss, they unseal Pazuzu. The demon gives them the Demon Summoning Program in hopes of using it for the defeat of Bael along with a warning of a coming menace. Demons then begin to raid the shelter and the two friends must save the remains of humanity.