Everyone Watch One Punch Man and Black Clover.

Gathered

There are various worlds out there that have their own people and their own environment. Some aren't as blessed as others and some were too violent and unpeaceful to live with. Some have much power with the help of technology and they usually call it their magic.

What if one day, they'll witness two worlds who may be more insane and more powerful than them? And how will they react to it?

Attack on Titan World

"Why all of us wanted to be at Wall Shina?" Connie asked as the members of the Survey Corps, Garrison, Military Police Brigade, and their commanders are all asked to enter a majestic building inside Wall Shina.

"Maybe they'll treat us with more food?" Jean replied with excitement.

"We should be preparing for the next Titan attack. Damn it!" Eren impatiently grunted.

"Calm down, Eren. Maybe this one is also important too." Armin said.

"Yeah, he's right. And besides, stop frowning all the time." Mina said.

"Fine! Do you even agree with this, Mikasa?!" Eren asked.

"Yeah." Mikasa replied.

They are all now outside the building and before Commander Erwin and Pixis open the door, it suddenly opened and a bright light blinds everyone and they didn't notice they were all dragged inside. After it, the doors closed and no one noticed what happened.

Hunter x Hunter World

"Gon, are you sure we can do this?" Killua asked as they were surrounded by the Phantom Troupe's Nobunaga and Machi.

"There's nowhere for you to go, brats. Give up." Nobunaga said.

"And maybe we'll settle things better back at the hideout." Machi added.

"Settle?! In what way?" Gon asked. A phonecall rang and Nobunaga answers it.

"Hello? What is it? Huh?! Feitan and the others were caught by some sort of mysterious light?! Hello? Hello?!" Nobunaga yelled.

"What happened?" Machi asked.

"Franklin called me about some light getting of our members in a blink." Nobunaga said. He didn't realize the light was there and he got disappeared in a second.

"What the--?" Machi uttered and she too got caught by the light and disappeared.

"Hey! What's going on? Gon!" Killua yelled as the light now shone on them and they disappeared in a flash.

Irregular at Magic High School World

"All students, please proceed to the gym? But why though?" Leo asked.

"Everyone's heading there by the way. Let's go." Erika said. They met Tatsuya and Miyuki alongside Mikihiko, Mizuki, and the others at the gym.

"Leo! Erika!" Mikihiko called.

"Hey there. I have one question on why they gathered us all here in the gym. Why is Ichijou and Cardinal Jorge together with their classmates here at our school?!" Erika asked as they looked at the other side of the gym and saw the other students from the other schools with them.

"Maybe a huge conference will be held here." Tatsuya said. A bright light appeared them all and they were all taken away in an instant.

In a huge cinema room, all of the people from their respective worlds were gathered in there and was surprised to see other people with them.

"Huh!? Where are we?!" Eren asked.

"Wh-Who are you guys?!" Mayumi asked in shock.

"Where's my CAD?!" Leo asked.