If this anime took place in Japan, 8 years after World War 1 ended, then why didn’t Demon Slayers use Fire Arms that shoots Nichirin iron bullets greased with wisteria oil to kill demons? Genya killed an Upper moon demon using a sawed off double barreled Winchester Model 1912 .

>1. If Demon Slayers took place in 1926 Japan, several years after ww1 ended, then why didn’t demon slayers use guns that shoots sun absorbing steel bullets wrapped in exploding wisteria oil to kill demons?
>2. if Demon slayers and sun absorbing steel Katanas don’t exist outside Japan, then Why didn’t Muzan escape to America and find the blue flower there?