Huh, that's weird. For me it happens right away at the title screen, with the pc9821ce2 driver, even after deleting the CFG file:
And the same goes for Schwarzschild GX (also a Kogado game) so it doesn't seem game-specific...
According to https://github.com/joncampbell123/dosbox-x/issues/1289
, 256 color mode ignores the lr value in the gdc which would explain this. Handling it is going to be a bit tricky though.