Prologue : What Happened?

This story is fanfiction of nihonkoku shoukan

Nihonkoku shoukan is made by minorou

All image is not mine

I'm still a rookie writer and if there are any suggestions and criticisms you can tell me

At the southern end of the globe there is a very powerful empire,An empire that ruled thousands of islands with its unparalleled navy and enormous economy but suddenly it disappeared from the earth, no one knew what happened to that empire