"Thousand Million" perhaps numbers work differently in Japan, but isn't that just a billion?
NVM, after some research it seems that before the part few decades that a thousand million was an actually number in Britain and that back then a billion was a million million.
It has quite a few generic isekai elements, but the tone it's set so far is nice. Seems like the manga equivalent of junk food: not great by any means, but enjoyable enough.