In our solitude | Tom Marvolo Riddle

It was may of 1988, many lives were sacrificed against the tyranny of Voldemort. And well, Harry Potter has once and for all ended the mighty reign of the dark lord.
Mia Heartstring, was not as lucky to be included in the numbers of those who survived during that war, caught in the midst of chaos and cursed by one of the death eaters as they terrorize the Hogwarts ground, she fell short at the age of 18 and turned to dust right after Voldemort was defeated.

The war was won, and she watched while everything ended in peace. As she rested under the schoolyard buried with other corpses of students and death eaters alike who also could not survive the cruel war.

Well, that's what supposed to happen if she wasn't standing in front of the school gate once more, the blonde girl once again an 11 years old attending her first day in Hogwarts school of witchcraft and wizardry.
Not only that, but it's not even the year 1981 when she originally attended the school herself, It is now July 1938. The year Tom Riddle started his first within Hogwarts.

Reincarnation? possibly, but why? and how? Why after the war had already ended? when she was in the midst of saying goodbye to the world and ascend to afterlife?