I realise I might be kinda late to the party here, but... how the on-site investigation going?
And by that I meant taking a trip to Japan and visiting the man himself (or what's left of him).
The Mu-soft domain is registered with a physical address, a house in Kyoto suburbs. A junior/senior high school is located 300m from the house, an elementary school even closer, if the rumors about Tofu being a teacher are worth anything. Admin's name, surname and phone number are all there too. I've only done a quick search on the high school's site and couldn't find any info about current/past employees but maybe it is there. The schools could also be contacted for info if only someone speaks the language and comes up with a good enough lie.
I don't really feel comfortable with posting all of that here (unless it's been common knowledge for a long time, it which case I just made a fool of myself) but all of the info I mentioned can be found in minutes, with barely any knowhow.
I know it's a huge stretch but if you're reading this and you're in Kyoto right now... You could become a hero for a small, sad group of people from a porn games pirating site.