Who is Rin Tohsaka?
The woman who survived every ending, even the stories where the hero was doomed to bite the dust;
The woman who could say, "I want them all!" in a story where the hero had to choose just one of three;
The woman who stole the spotlight in the other heroines' routes;
The woman destined to win at life, no matter which story route she took!
Strong, confident, calm, clever, decisive, knowing when to compromise and when to advance or retreat, with twin tails, a tsundere streak, the elegance of a perfect young lady, and the slyness of a crimson little devil. All of these qualities in one person make her perfect!
As the woman who got the true protagonist's script in Fate/stay night, young Rin Tohsaka unexpectedly awakened her Origin during a severe illness that nearly killed her. A consciousness with an Origin called "Transmigrator" merged with her small body, and from that moment on, fate turned in a different direction at the crossroads.
(PS: This is a reboot of an old work that flopped. If anything seems familiar, don't worry about it, because I'm just copying myself.)