Urano is the one who reincarnated as Maine in the beginning chapter. Though, it's kinda weird that Maine refers to Urano as a separate identity, considering most people who reincarnate in these types of novels refer to their past lives still as themselves. Really don't know how to explain it here.
I don't know the dark history thing though, but it's probably foreshadowing to something.
It's a bug.
Spoilers?
She died because she over reacted and saw a bug, thus causing her die from being crushed. Yeah.......
Eh? Wasn't that caused by a earthquake?
It was
It's a bug, it's just a literal "bookworm" eating her books
*cough* unlike Maine *cough*
about this page:
http://www.mangago.zone/read-manga/ascendance_of_a_bookworm/nbt/c012/pg-12/
please remind me, who is Urano?
and what does she mean by "dark history"?