ΔE 24.6, loose: different enough that you should pick on purpose. Sekigahara is a little lighter, much more muted than Mars Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Sekigahara is a little lighter, much more muted than Mars Red.
The same difference applies the other way round: Mars Red is a little darker, 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 Mars Red on the colour wheel See Sekigahara on the colour wheel
All matches: Mars Red equivalents · Sekigahara equivalents