ΔE 7.1, close: similar, with a visible difference side by side. Medieval Forest is a little lighter, cooler than IJA Nakajima Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Medieval Forest is a little lighter, cooler than IJA Nakajima Green.
The same difference applies the other way round: IJA Nakajima Green is a little darker, 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 IJA Nakajima Green on the colour wheel See Medieval Forest on the colour wheel
All matches: IJA Nakajima Green equivalents · Medieval Forest equivalents