Prompt by love-me-a-good-prompt on tumblr.

Gouenji couldn't understand how to pass the time. The place was crowded and he constantly had people bumping into him but he didn't try to strike a conversation with any of them and neither did they. They were too busy dancing, screaming and spilling their drinks all over the floor because of the aforementioned dancing. 

He was only there because it was Endou's party. He had invited the whole team and all of his old friends. It was a chance for them to get together and have some fun. And when he had insisted so strongly he couldn't turn him down even though he was in no mood for it. 

He decided to step out for a while and recollect himself. The constant commotion and being pushed around was getting to him. He took in the fresh air with a sharp inhale as he stood in the dimly lit garden. He paced around and then leaned against a wall looking aimlessly around. 

"Some party, huh?" A girl's voice startled him as he didn't see her approach him.

Gouenji turned to her quizzically. He  couldn't understand who was that girl who was speaking to him in a way that indicated that they were supposed to be well acquainted.  Her face was covered with a full-face mask that was decorated in a glittery skull style. She was wearing a purple dress and black boots and a cloak over it. 

He was certain it wasn't one of the managers because he recognised their voices and he had already seen them present inside in different costumes. 

"Do I know you?" He finally asked. 

" I'm supposed to be a witch. " She answered. 

"No, I mean, who are you?"  

"I'm a witch. Don't be thrown off by the mask." She elaborated. 

"That's not what I- nevermind. " He gave up as he realised he didn't care to know her identity.

"And what are you supposed to be?" She pointed at his regular clothes. 

"I'm supposed to be me. " He answered in a bored manner. 

"That's not how costumes work!" She seemed personally offended at the very idea of attending a Halloween party without a costume. 

"And you know how costumes work? You're a witch with a skull mask. " 

"I just put it on because I bought it as I found it pretty so I couldn't not use it. " She answered defensively.

Gouenji didn't respond and a few moments went by in silence. Then the girl spoke again,

"Anyway, why are you here and not inside?" 

"Just needed a break. " 

"That makes sense. " The girl slowly nodded pensively, "I need breaks too when I'm at a party. It's only good in small doses. " 

"You're kinda ruining it. " Gouenji commented under his breath but she caught on. 

"Oh, right! I should not talk. " She commented sheepishly and quietly leaned against the wall too. 

A few moments later Gouenji suddenly sprang up and made his way back inside. The girl with the mask followed him promptly. They were both greeted with the overwhelming sound of the loud music and the cacophony of everyone speaking at the same time. 

Gouenji picked a corner again and stood there watching the party scene unfold in front of him. The girl quietly stood beside him and fixed her gaze at him. 

"What are you looking at?" Gouenji finally asked her when she continued to stare at him.

"U-uh... nothing... just...." She fumbled for response and looked away.

Just then he spotted Endou waving at him from the other side of the room with Kidou standing beside him, both of whom then began making their way through the crowd towards him. 

"Oi Gouenji! You're here! We were looking for you all over the place!" Endou exclaimed loudly so as to be audible over the music. He was wearing a zombie costume and Kidou was supposed to be a vampire but Gouenji knew all too well it was just an excuse to wear his cape to the party. 

"Why didn't you dress up?! " Endou whined with disappointment. 

"I'm me. " Gouenji repeated his answer. 

"That's not how costumes work!" He exclaimed loudly. 

"You're not the first one to say that..." He answered as he turned to point at the masked girl but was taken aback to find out he was all by himself. 

"Who else said that?" Endou asked eagerly. 

"Weird, she was just here." Gouenji muttered pensively. 

"Who was here?" Kidou asked. 

"This girl, I can't recognise who she is but she was right here. She was wearing a witch costume but with a candy skull mask. Do you guys know who it might be?" 

"I haven't seen anyone here in this costume. " Endou responded, "Have you?" He turned to Kidou. 

"Me neither. " Kidou shrugged. 

"Are you guys sure? I swear she was right here! Up until you approached me. " He exclaimed as his confusion heightened and he looked around trying to spot her in the crowd. But she was nowhere to be found. 

"Maybe you had a run in with an actual spirit. " Endou teased, "Afterall tonight is their night. " He tried to say it in a spooky voice and Kidou rolled his eyes in response. 

"Funny. " Gouenji replied deadpanned, "Now help me look for her. I will prove to you I'm not making this up. " 

They looked around everywhere and asked their other friends but everyone only solidified that there was no girl in such a costume at the party. Gouenji was almost beginning to believe that Endou was right and the girl was in fact otherworldly. The thought unsettled him and he refused to accept it. 

"Just let it go and enjoy the rest of the party. " Endou suggested, ending their search mission. 

But now Gouenji couldn't think about anything else. The mystery was too intriguing to let go. How could he have a full fledged conversation with someone only for her to disappear into thin air? It was impossible.  

He stepped out into the garden again, hoping maybe there he would encounter her once more. He stood at the same place, in the same way waiting for something to happen. 

But this time he was left alone. There was no one around him and no one showed up even when he waited for half an hour. 

The party finally came to an end and Gouenji took a breath of relief as he was now finally free to relax. He made his way home, strolling casually on the sidewalk. The air was a little chilly and it was getting late but despite so groups of people could occasionally be seen, having fun among themselves. 

He hadn't gone far when he heard a loud "Hi!" from behind him. He turned and found out the same girl calling out to him from the other side of the street while waving at him. 

She did not wait for a response and skipped over to his side. 

"May I walk with you?" She asked and accompanied him as he moved forward. 

"You left so suddenly, you didn't even tell me. " Gouenji spoke plainly. 

"Did it bother you?" She asked with amusement as she turned and began walking backwards so as to face him. 

" No. But my friends think you're not real. "

"But I am right here and you're talking to me. " She chirped, still walking backwards. 

"They think you're a spirit. " 

"Do you think I'm a spirit?" 

"I don't know, you won't tell me who you are. " Gouenji answered, a little amused by this encounter at this point. 

"I'm a witch. I told you before." She replied the same way as before and chuckled a little, clearly enjoying the ambiguity she had created. 

"Why did you leave the party so abruptly?" 

"I wasn't welcomed there. " She answered, still maintaining the vagueness. 

"What do you mean?" 

"I wasn't invited. " 

"Then how did you find me in the garden?" Gouenji was trying to find a way to figure out who she was but she dodged every question with a vague answer. 

"I was just passing by and you just... caught my attention. So I thought I could get to know you. " Her tone indicated she was shy about admitting it. 

" Get to know me?" He chuckled, "All the while keeping yourself in mystery?" 

"I have answered all of your questions. " She exclaimed. She was still walking backwards, with surprising precision. 

Gouenji had now enough of her charades. All of a sudden, he held her wrist and pulled her towards him. She gasped loudly and froze in her place,

"What are you doing?!" She exclaimed. 

"So you're not a spirit. " He remarked as he fixed his gaze at her, smirking at bringing an end to her game.

The hood of her cloak fell off her head due to the jolt, revealing her shoulder-length brunette hair. Gouenji carefully removed the mask from her face shifting it to the top of her head. 

"I'm asking you one last time, who are you?" He asked in a low voice as he stared at her with interest. 

"I'm Kira. " She finally answered, her smile congratulating him on succeeding in finding out the right answer. 

"Why did you do this?" 

"Just because." She shrugged nonchalantly. 

Gouenji shook his head at the pointlessness of it all and let go of her. Leaving her standing there he made his way forward. 

"Wait! Don't go! Actually, you know what, I do have a reason, " Kira quickly followed after him, " but you see it's a very long story so maybe we should talk about it over coffee or something. " 

Gouenji stopped to give her a look of disbelief and then began walking again. Kira continued to walk alongside him convincing him of how good a story she had to tell earning a chuckle from him in response.