The First Progenitor

Y/n was a big fan of the monsterverse and attack on titan. On day because of a speeding truck and when she came to, she found out something wired. She was alive but not her anymore. She was instead a massive humanoid titan that towered over everything else in front of her.

She later finds out that she had been reincarnated into the monsterverse in the body of Ymir Fritz's founding titan form.