ΔE 9.1, close: similar, with a visible difference side by side. IJN Deep Dark Green is a little lighter, more muted, cooler than Black Forest.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). IJN Deep Dark Green is a little lighter, more muted, cooler than Black Forest.
The same difference applies the other way round: Black Forest is a little darker, more saturated, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Black Forest on the colour wheel See IJN Deep Dark Green on the colour wheel
All matches: Black Forest equivalents · IJN Deep Dark Green equivalents