I've been hunting for these things for years, dude...

Resources:

1. Archive.org
2. Angelfire and Tripod sites ghoulishly persisting
3. The Geocities archive project 3a. The Geocities searchable MIDI Collection
4. Ramuro's sakura.ne.jp website
5. MIDIshow
6. midiexplorer.tcl
7. Usenet
8. XDCC
9. Sailor Moon forums and mailing lists
10. The Lakh Dataset

Obstacles

1. Japanese character sets aren't handled well by standard MIDI programs
2. RCP files seem lost to time
3. The complete Geocities archive scrape is huge and requires a complete download 3a. Oocities has low server up time
4. File renaming conventions
5. JASRAC
6. Unsigned authors
7. Archive.org's archives are incomplete + didn't capture files
8. The death of NIFTY-Serve
9. Lack of diffusion of NIFTY-Serve MIDIs

Organising existing data

It would be really nice if I was just able to scrape every midi file off of the open web. That said, some people have done close to that for me; but that's really not enough. Some artists, like Rini Yoshiaki, never signed their MIDI files with any metadata, a title, or anything at all to signify it was them - except if you know the MIDI yourself or sourced it from an archive or reliable mirror.

Thankfully, most of the artists I know to look for did sign their MIDIs in some way. There's naturally going to be a lot more that didn't, and ever-so-frustratingly, I have had just about 0 success finding any RCP (recomposer) files. These were some early MIDI alternative files that were really common with the MIDI community on NIFTY-Serve, where tons of Sailor Moon MIDIs were made! So what do we do now?

Using MIDI Explorer to explore the Lakh Dataset

Ramuro released unfinished versions of his MIDIs from the 90s-2000s on a secret page of his blog. Using these, I may be able to find files with a similar key signature and tempo to find their finished versions - if they exist - in the Lakh Dataset. Part of me feels very devious, but the rest of me is very skeptical this will work, because I've searched everywhere for these MIDIs.

It's easy (for me) to hope a MIDI is out there. After all, sometimes things miraculously survive - for instance, the full Geocities mirror of Rini Yoshiaki's site that was discovered some years ago.

But while many of these files may have a surviving copy somewhere, MIDIs are considered to be iterative works by JASRAC (Japanese artists/creators copyright commission). They strike down people's Sailor Moon MIDIs even today. So I can't just hope for a copy within the Japanese MIDI-making community, but one that is uploaded somewhere that is not subject to JASRAC. Because of how little global penetration these NIFTY-Serve creations have had, that's not a very high chance.

It's made worse by the fact that many of these MIDIs were not originally in a MIDI format, but rather .RCP files, which have had even less penetration. We know that Ramuro's files received conversions, because he distributed them on his personal website throughout the 90s and 2000s. But as for the other creators, it's difficult to know if their RCP files were ever converted into MIDIs at all, and who converted them.

The golden goose of this all I think, might be Usenet. But it's a big 'might'... and maybe not.