The Forgotten (Twisted wonderland x Oc)

In this Au
We have an Oc from another world who first came in twisted wonderland before Enma Yuuken . Our oc who first came in twst mean that all who is in third year is in 2 year and the second year are in 1year .in this story our oc is the lover of the house wardens and the other characters who is in the love interest but since the principal figured out on how to send our oc back in her world .she decided to make a potion which can erase memories since she doesn't want to make her lover's suffer when she will leave and go back her world . Even the headmaster , the teacher's , and even malleus the strongest mage got their memories erased because of the potion that it was so strong. No one even remembered her not a single traced remained .
Also in this story when their memories got erased they didn't remember her but they always feel like their is something missing part of them and even a deja vu of someone that they don't remember.
What would their reaction when their memories will come back and how would their reaction when the history repeat itself just like the past happened , and how would their reaction when they found out that the history of the past is happening again all over again when their memories is back .
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(Before our oc go back to her world she put a secret pic and a letter hidden in the ramshackle dorm will Yuu able to found this letter or not how would yuu react that their was actually a way for him to go home but the headmaster forgot it because he got his memories erased...............What would their reaction when they will arrive to yuu world where our oc is also in that world . what would her reaction when they all reunited once again )
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(Will they even have the chance to talk to her before its too late )