Finally an isekai that doesn't have an artificial fiat currency totally coincidentally possessing the exact same value as today's yen. If it's the D&D looking one, like here possibly, then I don't care if a copper coin, for example, is worth exactly 100 yen. That can even make sense since it's a pretty convenient value for a lot of small things. Unsurprisingly, the D&D monetary system isn't totally disconnected from reality, unlike the usual isekai author's absolutely-not-yen currencies.
I wonder what that shadow is. One might think it's dark attribute magic, but the people in that world should be able to recognise that easily since it's an orthodox element. They even recognised Shizuru's lightning magic, even though nobody before him had it. Maybe it's a curse that prevents her from using magic.
Edit: Made my point a bit more clear.