Someone in the credits is credited for designing the manual... so somewhere out there, maybe on an old HDD or CD-r, is a completed Japanese manual for DDP
Heck there's probably one for Propeller Arena as well.
This would be incredible to get online. I can't think of another gaming "scene" that has ever done something like that - namely, find an unreleased game that was designed to be an online playable title, and then actually get it running online (especially 20 years later!)