User blog comment:RottenBlock/Toushin Toshi 1 Patch 1.5/@comment-80.144.159.180-20200411101948/@comment-40164738-20200413221333

I do remember running into a similar (if not the same error) when dealing with Rance II. I didn't really note it down as I thought it was just my computer using too much resources due to other programs and disk access bogging down. From what I remember it happened when I went through dialogue to quickly, but I'm not sure if that's directly related.

The only modifications I made at the time were a system 3.9 exe (Probably from the SDK) and probably some extra A and R commands, but I doubt that would mess with the music without horribly breaking any text to begin with.

Maybe it's some incompatibility with the system 3.9? I assume the games are very similar codewise due to their release dates, both originally and the windows ports.