The girl in the mist(A Nagisa x Oc fanfic)

Slow updates

One early morning at the beach resort, Nagisa looks out the window of her room to see that there was someone standing on the shore of the beach. He looked closer and could make the figure out to be a girl with long hair but due to the early morning mist, that's all he could see.

When the class arrives back at the school and go to the swimming pool that Koro-sensei set up, he sees the same girl from before, walking through the forest. Once again, he can barely make out to much about the girl but he can make out that she has black hair.

Will Nagisa find out who this person is?