Shin Megami Tensei is video game series by Atlus. They are mostly RPGs. The series includes Devil Summoner (Sega Saturn) and Soul Hackers (Sega Saturn and Sony Playstation, as well as the original Shin Megami Tensei games, found on Super Famicom. The Megami Tensei series, on Famicom predates these games, but are slightly different genre, and from a different company -- there was probably a purchase of rights in order to use the name and motifs.

The Persona series (called 'Revelations: Persona' in the US) is a gaiden, or side story of this series. These games include strong and frequest religious and occult references, from several different cultures. They also mesh the sci-fi and Fantasy genres quite well, involving both technology and magic. They have turn-based combat, and complex magic systems. In my opinion, the games have excellect plot componants, and very good music.