ΔE 11.6, fair: the same colour family, but not a straight swap. IJN Gray Mitsubishi is a little darker, more muted, cooler than Frost Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). IJN Gray Mitsubishi is a little darker, more muted, cooler than Frost Blue.
The same difference applies the other way round: Frost Blue is a little lighter, 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 Frost Blue on the colour wheel See IJN Gray Mitsubishi on the colour wheel
All matches: Frost Blue equivalents · IJN Gray Mitsubishi equivalents