It's a Grave of the Fireflies world and you have to protect Setsuko from Heartless while Seita gathers food. At the end Setsuko turns into a Heartless and you have to defeat it without killing Seita, who's protecting her. The Keyblade you get from the it is called Mosquito Net and it's special ability is that it makes Sora cry uncontrollably until it's unequipped. This is probably the worst idea I've ever had.
I'd just love to go into Naruto and Bleach and fight Madara and Aizen at peak strength. KH3 officially beats 2 of the strongest Shonen Jump characters ever, and quite possibly 2 of the most overpowered villains ever