ΔE 21.9, loose: different enough that you should pick on purpose. IJN Gray Green Nakajima is a little darker, much more muted than Aqua Alchemy.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). IJN Gray Green Nakajima is a little darker, much more muted than Aqua Alchemy.
The same difference applies the other way round: Aqua Alchemy is a little lighter, much more saturated.
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 Aqua Alchemy on the colour wheel See IJN Gray Green Nakajima on the colour wheel
All matches: Aqua Alchemy equivalents · IJN Gray Green Nakajima equivalents