These are games that have no known music rips in MP3. It may require tracking down native formats.

Fujitsu FM-7:
Digital Devil Story: Megami Tensei (Telenet version)

Game Boy:
Another Bible
Megami Tensei Gaiden: Last Bible
Megami Tensei Gaiden: Last Bible II

Game Boy Color:
Shin Megami Tensei Devil Children: Aka no Sho/Kuro no Sho
Shin Megami Tensei Trading Card: Card Summoner

Game Boy Advance:
Shin Megami Tensei Devil Children: Hikari no Sho/Yami no Sho
Shin Megami Tensei Devil Children: Honoo no Sho/Koori no Sho
Shin Megami Tensei Devil Children: Messiah Riser
Shin Megami Tensei Devil Children: Puzzle de CALL!

Game Gear:
Megami Tensei Gaiden: Last Bible
Megami Tensei Gaiden: Last Bible Special

MSX:
Digital Devil Story: Megami Tensei (Telenet version)

NES/Famicom:
Digital Devil Monogatari: Megami Tensei
Digital Devil Monogatari: Megami Tensei II

NEC PC-8800
Digital Devil Story: Megami Tensei (Telenet version)

NEC PC-9800:
Giten Megami Tensei: Tokyo Mokushiroku

PC Engine/TurboGrafX-16:
Shin Megami Tensei

PlayStation:
Shin Megami Tensei
Shin Megami Tensei II
Shin Megami Tensei if...

PlayStation Portable:
Shin Megami Tensei: Devil Summoner

Sega CD:
Shin Megami Tensei (SIMS version)

SEGA Saturn:
Shin Megami Tensei: Devil Summoner

Mobile Phones (IF POSSIBLE):
Aigis: The First Mission
Devil Summoner: Soul Hackers intruder
Devil Summoner: Soul Hackers new generation
Devil Survivor 2: The Extra World
Jack's Quest: Akuma Otasuketai
Majin Tensei blind thinker
Megami Ibunroku Persona: Ikuu no Tou-hen
Megami Tensei Gaiden: Shinyaku Last Bible
Megami Tensei Gaiden: Shinyaku Last Bible II: Hajimari no FUkuin
Megami Tensei Gaiden: Shinyaku Last Bible III: Mugen no Eiyuu
Persona 2: Tsumi -LOST MEMORIES-
Persona 2: Batsu -INFINITY MASK-
Persona 3: THE NIGHT BEFORE
Persona 3 QIX
Persona 3: CHAINING SOUL
Persona 3 EM
Persona 3 Social
Persona 3 Escape
Persona 3 Illust Puzzle
Persona: Ain Soph
Persona 4: The Card Battle
Persona Mobile Online
Shin Megami Tensei: Devil Children Mobile
Shin Megami Tensei: Devil Hunter ZERO
Shin Megami Tensei: Devil Collection
Shin Megami Tensei II Gaiden: Ma To Houkai
Shin Megami Tensei: if... Hazama-hen
Shin Megami Tensei: Tokyo Requiem
Shin Megami Tensei Pinball: Judgement