Mephisto (メフィスト?), also known as Mephistopheles (メフィストフェレス?), is a demon in the series.
Mephistopheles (also Mephistophilus, Mephistophilis, Mephostopheles, Mephisto and variants) is one of the seven princes of Hell. Originally appearing in literature as the name of the demon in the Faust legend, he has since appeared in other works as a stock character version of the Devil himself. A Greek name meaning "Not Loving Light", Mephistopholes is the demon associated with the Faust legend. He was especially prominent in the versions by Marlowe and Goethe. His name was also mentioned in passing in Shakespeare's "Merry Wives of Windsor".
Mephisto can be obtained in Rag's Jewelry after obtaining the required jewels.
Along with Belial, Baal, and Lucifer, Mephisto is one of the four Gaia Masters responsible for the monster outbreak. Shortly after revealing his role in manipulating the Zord organization to do the Masters' work, he is battled and slain. However, he secretly survives by devouring a monster, reincarnating him in a more demonic form, which can be fought at one of the shrines. Unlike the other Masters, he cannot be recruited after Lucifer is defeated.
Devil Children Fire Book
Mephisto is a minor antagonist and a servant of the Ice Apostle. He appears alongside the angels invading the earth, kidnapping children for their plans. He brings a "gift" for Jin that takes away the power of Rand and reverts him back to his original form. Later, he confronts Jin again and the two battle. However, it is revealed after the fight that he was an illusion. He is faced for the last time in the Ice Apostles Castle, where he once again attempts to take away Rand's power before being defeated.
After going on the quest to find all the revived servants of Ice Apostle, Mephisto will reside in a hut found in Sunefiyoru.
Shin Megami Tensei IV Apocalypse
Mephisto is fought in the DLC quest "A Trip to Hawaii".
After accepting the quest, he appears before Nanashi, offering a contract that allows him to experience the joys of a faraway tropical island, a luxury not known to people of his time. The player can end it at any time with the phrase "Stay, thou art so beautiful". Should the player accept, he gets drawn into an illusion where he enjoys his time at the beach with his companions. But eventually, the player is sent into a loop of events that can only be broken with "Stay, thou art so beautiful", as agreed on the contract. Mephisto then attacks Nanashi to collect his payment of Nanashi's soul.
Alternatively, before the illusion even begins, Nanashi can opt to say "Stay, thou art so beautiful". Mephisto is amused at his impatience, and attacks him regardless.
Mephisto is fought twice in quick succession, with Dagda intervening in between to break the player out of Mephisto's grasp. Defeating Mephisto unlocks him for fusion.