@Feha
I know girls that wear such shoes, and the shoe didn't look to actually be military
That unfortunately wouldn't make sense.
Firstly, these shoes don't look the kind of shoes a girl would wear, also the female zombies including Kei are all students of this school. We can safety be certain that they are all students of this school as mentioned in a previous chapter they still hold some form of past memories and return to those recent, regular places they vaguely remember. The main point here is that they are all wearing school uniform which the shoes look nothing alike.
Secondly, the trousers above the shoe has a militaristic pattern on them matching those on ch.73 page 3. Randall at this point, don't appear to be part of any military but it's own research organisation investigating Nazake Marsh, the origin of this bacteria/virus, which is off limits to the public but some staff member didn't follow policy and released the bacteria into the public.
It could be that Randall and the soldiers seen on ch.73 page 3 (with the same helicopter as as shown on ch.72 page 2) are two separate groups even if they are using the same bowman software. The helicopter and soldiers in this chapter are the same ones from v.4 ch24 Pg.24 who attempt to visit the school but failed when he got (airborne) infected and crashed the helicopter (if he was going to save or kill them).
We are still missing out on the Garrison (the military base) mentioned in both the manual and broadcast 954khz also the Central Hospital mentioned in the manual. Randall would probably kill anyone to cover-up their errors but now the military are involved.
REF: https://mangadex.org/chapter/564369/comments#post_512578
REF: https://mangadex.org/chapter/511349/comments#post_418699