Much as I love the original sketch, I think I'd be nice to see some colored version of this! They both have a light brown tan to their skin tone and dark brown eyes, and a dark grey streak in their bangs.. and aside from the streak, Mugen has jet black hair, and Haruka has mostly white hair~
I think it should be fairly easy to color, as it's a load of just black and white for the whole image, but if it could be refined by turning it into line art and coloring it, it'd be greatly appreciated!
And here are the images this sketch was based off of if anyone's a stronger reference of colors~