You were in your world and just doing training and a portal appears out of nowhere and pulls you in.

You arrive in this 'place,' the portal throws you on the ground, and instantly you recognize that you are in Tokyo Revengers. A boy comes in front of you and helps you up with a look, and you see that it's simply Manjiro Sano.

Manjiro had no idea about another reality or world.

Manjiro: Hey, are you okay?

Manjiro looks at you