This is basically just a reveal trailer, not a fanfiction. Sans was sitting around in his house. It was a normal day. Papyrus was right outside, then saw a letter put into Sans' mail. He dismissed it, thinking it was another letter Sans would ignore. The letter didn't fit, and fell onto the ground. Sans walked outside for no reason, then saw the letter on the ground. He would've ignored it, if it weren't for that mysterious red stamp on the front. "huh. wonder what this is." Sans opened the letter then was greeted by a shocking but unfamiliar message. "heh. they want me in "smash"? never heard of it. guess i'll go anyway, i don't have anything better to do." Sans' tagline appeared as he shrugged. Sans quits slacking! Sans is shown to be in Smash Bros. Ultimate. At the end of the trailer, completely black, it says "OH! I'VE GOT MAIL TOO!"