Didn't encounter "gyaru" due to not living in Japan, but judging by description of lots of tan, frisky clothing, etc. plenty are horny as fuck. Maybe two out of a dozen were somewhat shy, needed an actual month but the rest was just fucking, no sex just straight out fucking.
Now the most were false alarms, from daddy issues, having loose moms which they inherited that kind of outlook on life (bad parenting, ahoy!) or be confident through the style, hopping from one relationship to another.
The two not actually messed up in the head, kinda nice, but their parents+rest of family were interfering+toxic with everyone they met.
But hey, I'm not a scientist and surely know all.
Anyway, back to manga... is she trying desperately to make him loose the job on purpose? Because that's selfish...