Holy Sword of Two Family

It almost midnight, The four of them returned to their respective rooms. 

"Good night." 

"Good night, Miss Adeline."

Before that, the three of them escorted Adeline to her room. Adeline initially refused, but they insisted and finally escorted her to her doorstep.

She opened the door and closed it again. Cold air carried away by the open balcony window. She closed the balcony and felt something strange.

What was that? There is someone in this room.

"Who's there? Show yourself?"

The person showed himself. But, she can't see his face because covered by his robe

"Who are you? Why are you here? Do you have something to do with me?"

"Adeline? It's me. You don't remember me?"

Who? Have we met before? That person drew closer to me and I walked backwards to get away. Stopped because the balcony door was closed. I tried to open the door without his knowledge. But, the door was locked. How come? Since when he lock the door?