Yup. They are test subjects although one of them doesn't get tested on until further on.
Basically the protagonist of the comic (A 11 year old girl named Sophie who is later nicknamed Seb due to her subject code being SB-24) is being mugged and a woman, Anyi (cause her subject code is ANY-9) sees it and punches the guy. So yeah you were basically right.
Also to the other person there is actually a lack of light cause its raining so its dark but thats not why they don't have faces Lol I did that so their ethnicity couldn't be told by any facial features, that's why they are also grey. Oh and because when I draw that I could only do anime eyes.