MHP3 Custom Quest Creation Kit
A complete toolkit to create custom quests for Monster Hunter Portable 3rd (PSP / ULJM05800) entirely on a PC, merge them into the event-quest save MHP3RD.BIN, and distribute them freely. The Chinese MHP3TaskEdit editor and the crypto tools were reverse-engineered, translated (JP/EN), modernised and automated.
- The kit contains no game data (no ROM/ISO). You must own MHP3rd yourself.
- The game-specific key gamekey.bin is NOT included; you must obtain it yourself to build BINs (see below).
- Use modded saves at your own risk. Online (ad-hoc) use is NOT allowed.
- Always back up your save data before working.
What can it do?
Edit a quest's star rank, type, map, time limit, rewards, continuation, monsters (species/size/HP/attack/defense/stamina), supplies, gathering, material rewards and quest text. MHP3RD.BIN is doubly encrypted (PSP save crypto + MH's own crypto); both layers were analysed and verified to be processable on a PC, and the edit → encrypt → build-distributable-BIN flow is automated.
What's included
| Folder / file | Description |
|---|---|
| MHP3TaskEdit_日英版/ | Main editor (recompiled & bilingual MHP3TaskEdit) with a quest-list sidebar: open a BIN, edit, and build a distributable BIN in one go. |
| BIN化ツール/ | Layer-A crypto (endecrypter.exe) + automation pipeline and PAT/data.bin scripts + a sample plaintext BIN. |
| endecryptQST/ | Layer-B crypto tool (driven automatically by the pipeline). |
| 仕様書.md | Full specification, usage and analysis notes. |
| 企画書_53クエスト.md | 53 designed custom quests with tool input values. |
Requirements
- Windows (no PSP hardware needed)
- .NET Core 3.1 Desktop Runtime (for MHP3TaskEdit)
- Python 3 + pip install pywinauto capstone pycryptodome (for the BIN automation)
- PPSSPP (to play on PC) or a CFW PSP
🔑 gamekey.bin (not included)
Building/decrypting MHP3RD.BIN needs the 16-byte save key for ULJM05800. As a game-specific secret, it is not bundled. Obtain it one of these ways and place it at BIN化ツール/gamekey.bin:
- On a CFW PSP enable the SGKeyDumper (or SGDeemer) plugin → save/load MHP3 → ms0:/PSP/GAME/SED/gamekey/ULJM05800QST.bin appears; rename it to gamekey.bin.
- Or obtain the key shared in the old MHP3 modding community. Do not redistribute the key — it is game-specific.
Note: a finished MHP3RD.BIN is common to all PSP/PPSSPP, so it works on anyone's save and can be distributed (the key itself is never distributed).
Two ways to play
Route A (easiest, no PSP crypto): CWCheat PAT
Export a .pat cheat from your quest → load it via PPSSPP/CWCheat → load an event quest in the gathering hall → turn the PAT on → select the quest. No BIN editing needed.
Route B (build a distributable BIN): data.bin → MHP3RD.BIN
Build the BIN via the MHP3TaskEdit sidebar or `mhp3bin_auto.py build`, then place it in PSP/SAVEDATA/ULJM05800QST/. Anyone can use the same BIN, and anyone can build their own with the same steps.
See the bundled 仕様書.md and the README files for full instructions.
Notice & disclaimer
- The kit contains no game content. Each tool's copyright belongs to its respective author.
- gamekey.bin is a game-specific secret; do not redistribute it publicly.
- Use modded saves at your own risk; no online use; always back up important saves.