I don't know if this goes against whatever the plan going forward is, but if you need someone to handle Japanese Sega releases I can definitely do that. I own
this book which have full lists (up to date of publication, which was 2002) of every game released in Japan on at least the Master System/Mark III, Mega Drive, Saturn and Dreamcast. It gives the title, genre, and release date, so that's something to start with. It doesn't list variations (so there's just a general "Sakura Taisen" release date, not Sakura Taisen, Sakura Taisen LE Box A, Sakura Taisen LE Box B, etc) but I thought it'd be better than nothing.
If you want me to go ahead just let me know and I can get started once I've added most of my own games to the site, so realistically I can get going in a couple of weeks if you want.