One

It all started on that tragic day 15 years ago.

Kirishima Akane had somehow managed to put the happenings of her near-death experience that day behind and move on with life- settling into college life and blissfully planning a birthday-date with her closest friend. Little did she know that she'd just conveniently... cease to exist?
Petrified, she watched as the life she had lived thus far got taken away from her- no- as she got taken away from her life.

Everything had started on that tragic day 15 years ago.

...or had everything ended that day?