18 years later, I finally understand what "The World Ends With You" means

"Listen up, Phones! The world ends with you. If you want to enjoy life, expand your world. You gotta push your horizons out as far as they'll go." -Hanekoma

This title drop says it all. I didn't really understand it in 2007, but I understand it now in 2025. Neku starts as a loner, he doesn't "get" others and likely doesn't interact with many different people. His world was for himself alone. It was the boundary he had set. He then finds himself in the predicament of the Reaper's Game. The catch is that he has to rely on a partner to survive. This is something that directly challenges his world's boundaries. After he goes through everything in the game, we see him in the credits by the end. He now is sharing joy with the people he met in his story. By opening up to them, he expanded his world past himself. The world ends with you. You decide how big that world is.