It's hallow eve! Everyone was out trick-or-treating and so did you! You knocked on probably 6 doors now. From afar, you see someone... with a jack o' lantern as their head? Weird, but it's probably their costume anyway. You decided to go knock on some more doors. During one knocking, you get sent into some weird place, looking like a graveyard. The person with the jack o' lantern head was back, looking directly at you, then, they spoke up.

"heya, kiddo. nice trick-n'-trickin' out there? the name's sans, or jacko. say, how 'bout this? i give you a nice sweet sweet treat, but ya gotta beat me. good? eh, doesn't matter, witching hour starts now."

BATTLE, START!