Camellia Chronicles I : the Hydrangea Spring (previously Kristalyne Heart)

500 years ago, the eastern half of Terre disappeared into the ocean, leaving nothing and no one behind

450 years ago, the country Wisteria was established from the broken pieces of many states.

414 years ago, war broke out. It was the biggest and only war in Wisteria's history to this point, and yet during it no one realized a thing about it.

But this is all things that are said in the school textbooks, and thus slightly inaccurate. They also left out one major thing:

'History repeats itself, it will all happen again
and again
and again'

Nanami is a mostly normal girl who was chosen as the heir for her family, out of her 3 other sisters. Before she leaves to go to the capital for the sake of training to take on her family's role, she finds a journal entry from when she was in elementary school, a time she has no memory of whatsoever.
In the capital of Wistol, she must find a way to balance school, work, and friends she never knew she had before, as she struggles to find what happened in her past and why she can't remember it, while also fighting a possible recurrence of the War.

(This is still a huge work in progress lol)
(3rd revised version)