I've been working on a very rough redesign for DCMS ranks for a variety of reasons. The foremost one is that differing levels of ranks distinguished only by colour would not work in any military organisation because it is not practical and will cause confusion. Should an insignia get discoloured or dirtied on the field, or if you were colour-blind then it becomes very difficult to identify quickly if the person shouting at you is a Private, Kashira-Sergeant or Major!
This is how the original ranks look like in black and white (thanks Paladin Brewer for the compiled list on his site):

Immediately we notice problems with having common symbols for multiple ranks. Armed Forces do use different colours for SAME ranks on different uniforms; like gold for parade uniform, black for combat dress and a big giant one for PT, but will never use different colours and the same symbols for DIFFERENT ranks.

Also as pointed out, the "fourth" officer rank is missing for some reason. I think it was a mistake on the part of the writers/designers when they removed "2nd Lieutenant" but forgot to shift the subsequent ranks down by 1 number. An alternative explanation is that Japanese people have a superstitious fear of the number "4" and hence it was skipped but that is really offensively racist and doesn't account for the presence of Gun-sho and Sho-sho.
My redesign incorporates existing elements of the original ranks (I really like the use of numerical Kanji), draws a little from Japanese culture and is arranged roughly like today's JSDF ranks:
COLOURED TEXT DENOTES ORIGINAL RANK COLOUR.

The diamond bands are based of the hilts of kantanas, symbolising the base of a sword.

Continued use of original Kanji numerals to tie it to past lore.

The sword representing the fighting edge of the DCMS. A symbol of strength and pride and the soul of a warrior.

For those closest to the Combine, they wear the crest itself. These people are responsible for large swaths of territory and over many lives.
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I know that changing things in canonical lore can be upsetting to the community but I feel that this area requires an update in order for the DCMS to make sense as an organisation. Well, what do you guys think? Do I have a case?