Hades's Belly is a location in Kid Icarus: Uprising and is the location for the land battle of Chapter 23. While in Hades' Belly, Pit cannot communicate with Palutena or Viridi, so he must navigate the area himself. Most of the enemies encountered in Hades' Belly are cellular versions of Underworld troops. The boss for the chapter is Hades's Heart.
Though called Hades's Belly, this strange place is in an entirely different dimension than Hades. So while it shares a link of sorts with the evil god, it seems that destruction inside the belly barely affects Hades himself.