Loki (ロキ, Roki) is a recurring demon in the series. He is the primary antagonist of the original Digital Devil Story: Megami Tensei novel, as well as the cult-classic anime adaptation it spawned. Similar to the Norse Mythology, Loki is portrayed as being rebellious and tricky; but at the same time, possesses a cruel and ruthless personality. In Shin Megami Tensei series, Loki appears as a high level demon; capable on to recruit once players reached a sufficient high level. Furthermore, in the Persona franchise, Loki appears as a high level Persona, and is more often associated with the Fool Arcana.
"A major Norse deity, known as a trickster who clashes with the other gods. Blood brothers with Odin, but was later punished for his role in Balder's death."
Loki serves as the major antagonist of Digital Devil Story: Megami Tensei. Akemi Nakajima summons Loki and has him get revenge on several students at Jusho High School. Loki seizes control of several students bodies and murders the students that Nakajima wanted revenge on. Loki then demanded women be sacrificed to him, eventually allowing him to impregnate Ohara, one of Nakajima's teachers. While Nakajima was no longer watching, Loki practiced at teleporting through computer screens and taking physical form, which he eventually uses to rape and kill Yumiko Shirasagi, one of Nakajima's fellow students who happens to also be the reincarnation of Izanami. Nakajima attacks Loki with Cerberus and then escapes to Asuka, where he plans to resurrect Yumiko. Loki, angry at being injured and fearful of Nakajima summoning other demon lords that could compete with him, follows Nakajima to the tomb with the hopes of killing him. Loki kills Yomotsu-Shikome and he causes Yumiko's body to rot and attack Nakajima in an attempt to break his spirit. Izanami appears to fight Loki, but Loki captures her and prepares to rape her. Nakajima manages to summon Hi-no-Kagutsuchi as a sword and uses it to kill Loki.
Megami Tensei
Loki appears in Megami Tensei as a secondary antagonist. Lucifer resurrects Loki for him to aid him in the takeover of Earth.
Shin Megami Tensei III: Nocturne
Loki appears as a recruit-able demon in Shin Megami Tensei III: Nocturne. He can be recruited should the Hito-Shura's Lv. is higher than Loki's initial Lv, 52.
Persona 3
Loki appears as one of the Persona of the Fool Arcana in Persona 3. He can be summoned once the Protagonist reaches Lv. 55 or above. Loki, along with Susa-no-O also grants the Protagonist the Fusion Spell Trickster, which inflicts multiple mental ailments upon all enemies, alluding their roles as 'Tricksters' among deities.
Persona 3: FES
Loki returns as the Persona of the Fool Arcana in Persona 3: FES, retaining all of his attributes. In the playable epilogue of FES, titled The Answer, Aegis can also summon Loki by fusing the appropriate Personae.
Persona 4
Loki appears as the Ultimate Persona of the Fool Arcana in Persona 4, sporting a notable different design. He is available to be summoned once the Protagonist manages to gain access to the Normal Ending route, which maxes out the Fool Arcana Social Link. Furthermore, he can only be summoned once the Protagonist reaches Lv. 64 or above.
Loki also holds the distinction of being able to learn the most powerful Ice Elemental skill throughout whole game, Niflheim.
