now that you mention it, I'm pretty confused about the source of that information myself. Hajime Wakai is at least credited for "STAFF ROLL" on the guitar arrange album, though "All Need is 30 Deaths" isn't on there. the
pony canyon page for the album lists a full breakdown for all the tunes though. that's as close to an official source for the info as i can find at the moment. maybe they do say something about it in the commentaries for the albums.