The Multiverse was a realm of many worlds. Some far different than the ones Sora had previously visited upon his journey. With the power of the Keyblade, Sora was able to open portals to any world, then traverse to it with the Gummi Ship.
Normally he was accompanied by his --
-- one called 'Earthland'.
Landing the mysterious, world-traversing craft at a location mostly out of the sights of those that inhabited this world, Sora wouldn't hesitate to run off to explore this new world. His clothing and form seemingly didn't change, so it was likely --
“It's the ones who don't look like bad guys who are the real bad guys.”
“I’ve got enough weight on my soul as it is. I don’t need a kid getting killed because of me added on top.”
“Great.”
“You know, I find it hard to believe you’re a fighter. You’ve got this whole Shonen air to you, but not in a G*** sort of way. More like a P**** of T***** sort of way.”