Cerberus

Cerberus (ケルベロス, Keruberosu) is one amongst the earliest of demon allies to appear as part of the Megami Tensei franchise. His roots put him as far back as the very first Digital Devil Story: Megami Tensei publications. He typically appears as a white dog with a lion-like mane, unlike the Cerberus of Greek mythology. In Japan, Cerberus is rendered Kerberos, which is also the Greek pronunciation.

History
Cerberus in Greek and Roman mythology is a monster that guards the gates of the underworld, the realm of Hades and the dead. It is generally depicted as a vicious, gargantuan dog with three heads, although accounts may vary.

Clarification
Cerberus is in fact the Latin romanization of the Greek name Kerberos. The dominance of Latin throughout the modern Western World was for many centuries precipitated by functionaries of the Roman Catholic Church. However within contemporary non-denominational academic discourse, the use of Latin for non-Roman words is in sharp decline.

Appearances

 * Digital Devil Story: Megami Tensei: Nakajima's demon familiar
 * Digital Devil Story 2: Warrior of the Demon City: Nakajima's demon familiar
 * Megami Tensei
 * Megami Tensei II
 * Shin Megami Tensei: Majuu Race
 * Shin Megami Tensei II: Majuu Race
 * Shin Megami Tensei If...
 * Kyūyaku Megami Tensei
 * Shin Megami Tensei: Devil Summoner
 * Devil Summoner: Soul Hackers: Majuu Kerberos with three heads
 * Megami Ibunroku Persona: Fortune Arcana
 * Persona 2: Innocent Sin:
 * Persona 2: Eternal Punishment: Fortune Arcana
 * Shin Megami Tensei: Devil Children Black Book
 * Shin Megami Tensei NINE
 * Shin Megami Tensei III: Nocturne: Beast Race
 * Digital Devil Saga: Avatar Tuner
 * Digital Devil Saga: Avatar Tuner: Atma Avatar
 * Shin Megami Tensei: Devil Summoner: Raidou Kuzunoha vs. The Soulless Army: Pyro Class
 * Shin Megami Tensei: Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon: Pyro Class
 * Persona 3: Strength Arcana
 * Persona 3: FES: Strength Arcana
 * Persona 4: Hierophant Arcana
 * Shin Megami Tensei IMAGINE: Beast Race
 * Shin Megami Tensei: Devil Survivor: Beast Race
 * Shin Megami Tensei: Strange Journey: Beast Race
 * Shin Megami Tensei: Devil Children Red Book
 * Shin Megami Tensei: Devil Children Black Book
 * Shin Megami Tensei: Devil Children White Book
 * Shin Megami Tensei: DemiKids: Light Version: Nex
 * Shin Megami Tensei: DemiKids: Dark Version: Nex
 * Shin Megami Tensei: Devil Children Fire Book
 * Shin Megami Tensei: Devil Children Ice Book
 * Shin Megami Tensei: Devil Children Black Book/Red Book (PS)

Megami Tensei
Kerberos is encountered like any other devil near the end of the Daedalus Labyrinth within a corridor on the way to Valhalla. He is also featured on the game's startup screen and graphics, and appears in stills from the Digtial Devil Story: Megami Tensei anime printed within the game manual.

Megami Tensei II
Kerberos may be encountered and welcomed into the player's party via an optional side-quest which entails gaining access to what appears to be a Virtual Reality experimentation laboratory by which the player's party is able to re-enter the Devil Busters VR video game and continue re-tracing the alleged events of the first Megami Tensei game in this series. Kerberos is encountered inside the VR simulation approximately in the same area he may be found in the in the first Famicom game, Megami Tensei.

Kyūyaku Megami Tensei
Kyūyaku is a considerable Super Famicom remake of the original Megami Tensei games on the Famicom home video game console. The events involving Kerberos are similar for obvious reasons.

Shin Megami Tensei
After having his mom killed by a demon, the protagonist's can choose to add his dog, Pascal, into his party. In normal circunstances, Pascal serves as a low level ally. But when fused with a demon in the Jakyou Manor, he transforms into the high level demon Kerberos. Because of Pascal's former loyalty towards his master passed on to him by the fusion, Kerberos can be used even when his level far surpasses that of the Hero--what generaly is impossible. He aids him in only one battle however, disappearing through a teleporter after a boss fight.

Much later in the game, Kerberos stands on the bridge that leads to Tokyo Destiny Land, in a berserk state that can only be reversed if the protagonist possess a valuable item called "Golden Apple". Because of the power from this item to stabilize violent demons, Cerberus come back to his senses and recognize the Hero, thus choosing to share his fate by joining his party.

Shin Megami Tensei III: Nocturne
Cerberus first appears at the Burial Chamber in the Amala Labyrinth's First Kalpa, where it will challenge you to prove your worth as a demon by quickly vanquishing once more those that you have killed in the Vortex World using the Black Visor. After meeting all the requirements and starting a new cycle, meeting with Cerberus again in the same location will have him take you to his master's resting place instead at the Tomb of Yomi in the hidden 666th floor, where you will receive an extra Press Turn.

Cerberus can also be encountered and recruited inside the Diet Building.

Digital Devil Saga: Avatar Tuner
Cerberus is the Atma Avatar of Lupa, the leader of the Wolves. He serves as the boss fight in the Samsara Waterways. In this title, Cerberus appears as a three-headed, eyeless beast.

Shin Megami Tensei: Devil Children Black Book
Cerberus appears in Shin Megami Tensei: Devil Children Black Book as Cool, the demon companion to Setsuna Kai. Cool appears when Setsuna uses a Devil Riser to attempt to save his brother from Jack Frost.

Persona 3
Cerberus appears as Koromaru's initial Persona. It is a fire and darkness elemental Persona and differs from the usual appearance as a black three-headed hound. The original Cerberus can also be accessed and used by the Protagonist by using a cheat device.

Persona 4
Cerberus is a Persona of the Hierophant Arcana, usable by the Protagonist once he reaches Level 52.

Shin Megami Tensei: IMAGINE
Cerberus is the 2nd demon you acquire although in an injured state passed down from DB Kuroe after witnessing her death and treating Cerberus's wounds. He then insists on following you on your journeys as a fledgling DB, but is again taken to heal fully by Snakeman after Act 3. After reaching level 30, you can regain him again as an ally at full health. A 3-headed version of Cerberus may be obtainable with certain requirements achieved.