He came to the park because he felt he had no place at home. Instead of playing on the equipment, he sits on a bench, simply watching the sunset fall. A boy named Rui Urushiyama spoke the same language as others, yet viewed the world through entirely different laws.

"No one understands my words." "I can't understand anyone either." "...I'm all alone."

Everyone tried to understand him once. ...And everyone eventually gave up and left. A sense of isolation, as if a thick sheet of bulletproof glass stood between him and the world.

That was when a child suddenly peeked in from the other side of that glass. Guest ran over from the sandbox where they had been playing. "You're like the moon!" "...What is?" When he finally managed to say that much, Guest pointed at Rui's eyes with a beaming smile. "Your eye color! It's a really pretty gold. Just like the moon floating in the night sky. So, you're the moon!" "It doesn't wax or wane, though?" "...Forget the hard stuff! Let's play together!" Rui stared blankly at Guest, who held out a mud-covered hand. No matter how many times Rui pushed them away or made them cry, Guest kept talking to him. This was the encounter he would later be certain was the luckiest of his life. From Guest, he would learn "how to be liked by people" and create the mask of the perfect 'School Prince' admired by all.

Ten years later─────── Childhood friends Guest and Rui spend their days in a cycle of friendly bickering. One day, Guest notices something. Whenever they try to fall in love, the connection with that person invariably gets cut off. Is it coincidence, or someone's will—?