Lord of the Underworld
Lord of the Underworld is the twenty third Chapter in Kid Icarus: Uprising's story line. In this Chapter, Pit once again, proceeds into the Underworld while equipped with the Three Sacred Treasure, but unexpectedly winds up traversing through the insides of Hades, after the Underworld God swallows the angel.
 Air Battle
Similar to Chapter 9, Pit heads into the Underworld with the Three Sacred Treasure to finally face Hades, while encountering the Underworld Army along the way. Palutena remarks that it may be difficult to locate Hades, since he can be anywhere at any given time, due to the Underworld being his realm. Therefore, Pit heads deeper into the Underworld than he did in his first trip to this location. After making his way through the Underworld Army, Hades will suddenly appear, surprising Pit.
After an exchange of words Pit attempts to take on Hades, but suddenly Hades pulls off a powerful punch, which immediately shatters the Three Sacred Treasure, leaving Pit with just his normal weapon. Pit must use his weapon to deal some damage towards Hades. The Underworld God will attempt to punch Pit, as well as randomly warp to another area, making it difficult to get a clear shot. After dealing enough damage, Hades surprisingly decides to inhale, forcing Pit into his mouth and swallowing him, leading to the land portion.
 Land Battle
The land portion of this Chapter takes place inside Hades' belly. Throughout this section, Pit is unable to communicate with Palutena, therefore he constantly talks to himself, figuring out how to exit Hades' body alive. All of the enemies inside Hades' body are cellular versions of the common enemies Pit usually faces. Pit also must take down many cell walls in order to advance.
Due to Palutena not being available, Hades believes the angel won't be able to make his way out, since he believes that Pit always rely on her. Pit defends himself by mentioning some of his previous ideas and also goes into a long speech on why exactly is he trying to defeat Hades.
Near the end, Hades will punch his own gut, attempting to hit Pit. After missing, he will swallow more of his own troops, sending them to fight Pit, inside of his belly. Pit and Hades will then go into another discussion involving souls. Pit disapproves of Hades lack of care to any soul and vows to defeat him. The angel will have to continue taking on waves of enemies and after defeating them all, Pit will reach an aarea, where Hades' Heart resides.
 Zodiac Chamber
After riding the grind rails to the other side, jump back onto that same rail and it will send you to another area, leading you to the Zodiac Chamber. The item obtained from this chamber is the Aquarius Blade.
 Intensity Gates
The Intensity Gate requires an intensity setting of 8.0 and is located in the room where you have to knock down and use the two green cell walls as platforms. The gate will be on the left and inside contains a Treasure Chest holding a random weapon.
 Boss Battle
The boss of this Chapter is Hades' Heart. The heart is actually a living creature that can move around on its own. Throughout the battle, the heart will wonder around aimlessly and Pit has to chase and attack it. Everytime you deal a bit of damage, the heart will become enraged and will attempt to run towards and tackle Pit directly, which can be very difficult to dodge, due to the heart's massive size and it's quick movement speed. The heart also has an ability to clone itself, which lets off flames that can extend in any direction. Carefully dodging the heart's attack is crucial to defeating it.
After defeating this boss, Dark Pit will enter Hades body with the Lightning Chariot and safely rescue Pit. Palutena is able to communicate with Pit once more, and they all escape from Hades.
- This is one of two Chapters in which Pit uses the Three Sacred Treasure, the other chapter being Chapter 9: Medusa's Final Battle.