Hey so there's demons in this manwha, and there's also no specific period. it's a bit of a mix of periods, georgian, regency and victorian. eleven if it was a specific period, it's pretty accurate, even the flare under the vest
Well if we use our thinking caps we can realize this is fictional and not based of any specific time period from history.
Well if we use our thinking caps for a bit longer we can also realise that fiction takes inspiration from real experience and events. This is historical fantasy and if you have ever written any time of material you can realise that you need to do some type of research into the subject matter. Using modern clothes in a historical setting, is lazy not imaginative just because this is fiction.
I swear this author is clothes blind or something, because why does she dress the MC in these kpop-type outfits??? Her "hunting" outfit looks like she's about to go do a meet-and-greet and then perform her new hit single on stage. Nothing about her outfit matches the time period (づ￣ ³￣)づ