Mokoi can be found in the 1st and 2nd stratums of Naraku. It can teach Flynn the Zio and Dream Fist skills through its Demon Whisper.
Shin Megami Tensei IV Apocalypse
"An humanlike spirit of Murngin lore that lives in the jungle and moves at night. He is the reincarnation of the "shadow soul" of humans, and kidnaps and eats children, sometimes causing war with humans."
—Shin Megami Tensei IV Apocalypse compendium
Mokoi appears in Shinjuku at the south entrance and the west entrance passage, as well as the northern areas of the Fairy Forest, past the central gate. He can teach the Zionga, Head Crush, Dream Fist and Mazio skills during Demon Whisper. Mokoi has an affinity for Physical, Electric and ailment skills.
Devil Summoner: Soul Hackers
"An evil spirit of Murngin mythology, believed to be reborn shadows. They kidnap and eat children, and strike down sorcerers who use black magic."
—Devil Summoner: Soul Hackers compendium
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
"A human-like spirit of Murngin mythology that lives in the jungle. A Mokoi appears to strike down those who use black magic."
—Devil Summoner: Raidou Kuzunoha vs. The Soulless Army devil chart
Persona 4
"An evil spirit of Murngin mythology, believed to be reborn shadows. They kidnap and eat children, and strike down sorcerers who use black magic."
—Persona 4 compendium
Mokoi can be obtained through Shuffle Time in the Steamy Bathhouse. After fulfilling Quest 43, the protagonist will be rewarded with a Mokoi Doll that he can place in the shelf in his room.
Persona 5
"Evil spirits of Murngin lore believed to be reborn shadows. They kidnap and eat children, and strike down any sorcerer who uses black magic."
—Persona 5 background
Mokoi is the second Persona of the Death Arcana and can be found as a Shadow in Madarame's Palace and in the Chemdah area of Mementos, with the title "Night-walking Warrior." Mokoi is the first Personas accessible by the protagonist to learn Dekunda. When itemized through an Electric Chair execution in the Velvet Room, Mokoi yields a Dekunda skill card.
DemiKids Light & Dark
"A greedy earth demon that preys on the spirit of those with many years ahead of them."
"A humanlike spirit of Murngin lore that lives in the jungle and moves at night. He is the reincarnation of the "shadow soul" of humans, and kidnaps and eats children, sometimes causing war with humans."
—Devil Survivor 2 compendium
Shin Megami Tensei: Liberation Dx2
"An evil spirit from Australian Aboriginal mythology. It lives in the jungle and looks human, but it cannot speak for it has no tongue. It is known to kill those under the influence of black magic."
My name's Mokoi. A Jaki. I have tons of lady fans. You know, right?
...Guess it's time for a vacation. I hear Istanbul's nice this time of year.
Gallery
Mokoi as he appears in Devil Survivor 2
Mokoi as he appears in Raidou Kuzunoha vs. The Lone Marebito
Mokoi as it appears in Card Summoner
Mokoi in Persona 5 Royal
Mokoi in Persona O.A.
Trivia
Although it is, like any demon, optional to recruit or keep in the actual games, a Mokoi seems to make up a very important part of Raidou Kuzunoha the XIV's "canonical" demon team. In every single appearance Raidou has made outside of his own games where he summons demons (that is, Devil Summoner: Soul Hackers, The Lone Marebito and the "Chronicles" edition of Shin Megami Tensei III: Nocturne), the Mokoi has made a major appearance. It is so important in Chronicles, in fact, that it opens the cutscene before the fight between Raidou and the Demi-fiend, in addition to being one of Raidou's major attacks.
This Mokoi is often seen using abilities that are all but impossible for a playable Mokoi to possess, such as a powerful boomerang attack. It also has impressive (to say the least) stats when targetable in Soul Hackers.
The only other demon to feature so consistently on Raidou's team is Moh Shuvuu.
