Persona x Crossing Void

The Void in Mementos

Mementos, a dark tunnel, and a palace for everyone's hearts and Joker and his group are exploring and injuring, stealing, and blackmailing the shadows and it was a normal day for them to grind and level up until all of the sudden, a void calling them appeared out of nowhere. The gang stopped to check it out but was too cautious until they heard the sound of chains getting closer

"It's the reaper." Fox Exclaimed.
"Careful. That shadow is very strong and resists almost every attack." Said Oracle as she analyzed the enemy
"I'm not ready for that thing!" Skull replied in fear.
"We got nowhere to go," Ann explains the current situation. They seem trapped until Joker looks at the portal for a few seconds. The group looked at him with doubt but with nowhere else to go, they jumped to the portal. They fell with for seconds filled with lightning around as they scream fearing what happens when they fall.

They eventually  landed on debris as they got out of the portal one-by-one. They complained from their injuries until they saw a guy in a black leather outfit wielding a black and light blue sword. He seems to be battling a woman with green leather outfit and wings

"Uhhh are they fighting with each other?" Skull asks the group.
"No idea but we shouldn't interfere so let's go." Replied Crow

As they went aside, the girl in green leather clothing and white shorts notices and calls them out. The group heard her calling and and turned over to her voice. She prepared her stance as a sign of fighting. Akechi tries to reason out but was interrupted by the guy in black clothing. They have no choice but to fight. 

"Guess we have no choice but to fight huh?"
"Yeah that's right."
"Alright give me your best shot."
"The black leather swordsman tries to perform Spinning Shield. Joker dodges it swiftly due to his evasion. The Swordsman was in shock with his evasion while the green girl attacks Skull with wind. 

"Shit! She got garu skills. Futaba, a little help with the analyzing."
"I'm trying, try hitting her with your electricity."
"Go, Captain Kidd!"

The girl with wings dodged her attack. Skull attempted to attack her with agneyastra and she got hit with the last meteor. The black swordsman noticed his teammate has fallen has let his guard down. His rage has increased and performed his starburst stream. Each slice of his swords damages the phantom thieves physically one after aother. The only one left was Joker as he called out Yoshitsune and performed the Hassou Tobi. The slices of the persona dealt heavy damage to the black swordsman until he fell on his knees. Joker pointed a gun at him.

"Do it. Kill me." The black swordsman said in rage. Joker hesitates to shoot and the intense silence filled the air. Crow got up and tries to stop Joker from shooting him. He explains that they don't seem to be shadows nor cognition. Joker withdrew his gun and asked the black swordsman some questions. 

"Who are you?"
"I'm one of the biggest heroes in Aincrad, Kirito."
"Aincrad? Sure but where are we?"
"I have no idea. We also have been transported here through a portal. We thought it would be a good idea to check since we were already geared up."
"I see. Then how about you team up with us?"
"I don't know. How will we know that you won't attack us again? 
"We have traveled through the same portal too and we're on a mission to get back."
"Alright, I'll team up with you. Oh and I gotta heal up Leafa first."
"No need. We'll do it. Queen, if you may."
"Alright Joker." Responded Queen.

Queen ran to Leafa and casts diarahan on her. She becomes conscious and sees a woman in a battle gear outfit and a mask. She grabbed her sword beside her and pointed it at her. Kirito immediately told her to unsheathe her sword as they'll be joining for a while. Leafa is doubted on the fact a group of masked people are joining but decides to go along. Joker asked what they were doing earlier. Kirito replied with "We're just sparring." It seems reasonable for them since they're comrades.

"Might I ask though, who are you guys?" Asked Leafa

"We're the Phantom Thieves of Hearts."