Atlus's Megami Tensei spin-off for Game Boy Color. Recruit demons, fuse them, and fight through a Japanese setting.
Revelations: Demon Slayer was developed by Hect and published by Atlus for Game Boy Color in September 2000 — a port of the 1999 Game Boy Color title originally released in Japan as Mōryō Senki MADARA. The game featured a protagonist who could recruit demons as allies through negotiation, fuse them to create more powerful demons, and battle through a mythological Japanese setting. The demon recruitment and fusion system was a simplified version of the Shin Megami Tensei mechanics. Revelations: Demon Slayer sold approximately 200,000 copies and introduced Western players to SMT-adjacent game mechanics.
About this game
Revelations: The Demon Slayer is the 1999 Game Boy Color re-release of Megami Tensei Gaiden: Last Bible, a 1992 RPG originally published by Sega for the original Game Boy. The game follows El, a young Gaia magic user, who must stop the Gaia Masters from unleashing monsters on the world. Its core mechanic — recruiting and fusing demons into increasingly powerful allies — is a direct adaptation of the Megami Tensei demon negotiation and fusion system. The North American localization by Atlus in 1999 was notable as one of the first colour RPGs published on Game Boy Color in the region.
Gallery
The Story Behind
The Last Bible series was Atlus's attempt to bring the Megami Tensei universe's demon recruitment and fusion mechanics to portable hardware, targeted at a younger audience with a less dark aesthetic than the main SMT titles. The 1999 GBC re-release coincided with Atlus's growing Western presence through the Persona and other Shin Megami Tensei related titles, and the Revelations branding — shared with Atlus's localization of Persona as Revelations: Persona in 1996 — was part of an attempt to build a Western Megami Tensei brand identity. The North American release was historically notable as among the first GBC color RPGs published there.
Tricks & Tales
Revelations: The Demon Slayer uses a simplified version of the Megami Tensei fusion system — two allied demons can be combined to create a new, more powerful entity. This mechanic, which was radical in the main SMT series, is adapted here into a friendlier interface aimed at Game Boy players. The game's demon roster draws from Atlus's library of mythology-based demon designs. The Revelations branding was used in North America to connect Last Bible with Persona (Revelations: Persona), creating a loose franchise umbrella that predated the international recognition of the Shin Megami Tensei name.
Collector's Guide
Region & Compatibility
Originally released in Japan as a Game Boy title in 1992, re-released for Game Boy Color in Japan in March 1999 and North America in August 1999. The North American version was localized by Atlus under the Revelations brand. The Japan GBC version features colour graphics; the 1992 original was monochrome Game Boy.
Maintenance Tips
Game Boy Color cartridges — the smaller, slightly translucent-shell format — use the same cleaning approach as original DMG carts: a cotton swab with 90% or higher isopropyl alcohol wiped along the contact row, allowed to dry fully before reinsertion. The GBC console's ABS plastic shell faces the same yellowing risk as the DMG when exposed to UV light over time. Notably, several GBC titles — most famously Pokémon Gold, Silver, and Crystal — include a real-time clock (RTC) circuit that runs continuously off a CR2025 coin cell. These batteries are now well over 25 years old; a dead RTC battery means time-based in-game events will not advance, even though the game itself will still load and save normally. This is a distinct issue from save data loss.
Going deeper
Explore the machine this game ran on, and what to check before you buy or care for one:
What to Watch Out For
Before buying, these are the points worth knowing — from someone who handles original Japanese Revelations: The Demon Slayer copies regularly.
Is this a region-free game? Will a Japanese Game Boy cartridge work on any Game Boy console?
Yes. The original Game Boy, Game Boy Pocket, and Game Boy Color have no hardware region lock — a Japanese cartridge plays on any Game Boy or Game Boy Color console worldwide without modification. The game itself is in Japanese, but the hardware accepts it freely. Game Boy Advance consoles are also backward-compatible with Game Boy and Game Boy Color cartridges and share this region-free status.
How should I clean a Game Boy cartridge?
Apply 90% or higher isopropyl alcohol to a cotton swab and gently wipe the gold-plated edge contacts on the base of the cartridge. Never blow into the cartridge — breath moisture accelerates contact corrosion. If the shell needs to be opened for deeper cleaning, Game Boy cartridges use 3.8mm security game bit screws. The contacts are small; clean with a gentle wiping motion rather than abrasive pressure.
Before You Buy
Things worth knowing before you buy Revelations: The Demon Slayer
A short checklist for buying a used Game Boy Color cartridge wisely — useful with any seller, anywhere.
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Choose a seller who tests it before shipping
A copy that has actually been powered on and checked is a known quantity. An untested one is a gamble you only settle after it arrives.
Look for a seller who states it was function-tested and says what they confirmed. A serious seller can tell you exactly what was checked.
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Good news — Game Boy Color is region-free
These cartridges are not region-locked, so a Japanese copy plays on any compatible Game Boy worldwide.
Confirm whether the title is Color-only or also works on the original Game Boy.
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If this title saves your progress, check the battery
Cartridges that save use a small coin-cell battery that fades over decades — a dead one wipes your save without warning.
Ask the seller whether the save function was tested. Replacing the battery is possible, but doing so erases any existing save.
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Check that the contacts are clean
Dirty edge contacts are the most common cause of startup and sound trouble in cartridges of this age.
Choose a seller who cleans the contacts before shipping. A note that it was tested and cleaned means the basics were handled.
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Read the seller's reviews and return policy
A 100% positive record across thousands of sales is close to a guarantee — packing, communication and problem-solving all work for everyone. A return policy protects you if something is off.
Read the feedback and confirm a clear return window before you buy.
The last step before buying anywhere is knowing what it's worth.
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