Intestinal Inspector
Intestinal Inspector starts with Lo Wang finally getting closer to the dragon. Your objective will be to get inside it and kill it once and for all.
Completing this part of the game will unlock the trophy/achievement "Dragon Slayer."
Reaching the dragon's head
Once the cinematic is over, you'll be on the dragon's back again. Move forward following the path and deal with any enemies in the area. Remember to shoot the rock instead of the enemy to make it fall whenever you see an enemy on top of a rock with yellow bits. Your first big demon fight will happen after sliding down a path and getting to a fleshy area full of enemies. There'll be tons of different demon types, so prepare for trouble.
After killing all the Yokai, shoot the Demonic Thorn and use the grappling hook to keep moving forward.
Your second big demon fight will come shortly after the first one. After killing all the enemies, shoot the Demonic Thorn and keep moving; you'll have to deal with a few Oni Hanma next, kill them and keep moving.
A cutscene will start where the dragon throws you to another section of its body. Once the cinematic is over, move forward to get to another area where you'll have to fight a couple more demons.
After dealing with them, shoot the Demonic Thorne and go up the vine-covered wall to keep moving towards the dragon's head.
Keep following the path, and eventually, you'll get close enough to the head that you'll be able to go inside the dragon through its mouth.
Reaching the Dragon's Heart
Upon entering the dragon, a cutscene starts where Lo Wang retrieves Hoji's mask from the raccoon's body and goes further inside the beast.
Once the cutscene is over, keep moving forward, following the path. In this new level, you'll use a unique mechanic that's nowhere to be seen in other sections of this game, the green "puddles."
These puddles are round, green objects on the floor that act as a trampoline, launching you forward when you step on them.
Keep moving through the level by using Lo Wang's skills, like wall-running, the grappling hook, and double jumping.
You'll reach an area full of demons, so deal with all of them to keep moving forward. Once the fight is over, shoot the Demonic Thorn and use the green puddle to reach the rock ledge in front of you.
Keep moving, traversing through the obstacles until you reach another area with demons. This one is a little bigger than the last so you'll have more walking room.
Once you've dealt with all the demons, clear the Demonic Thorn and keep following the path through the dragon's insides.
Activating the Doomsday Device
Once you reach Hoji's Doomsday Device (the one you helped him activate earlier on in the story), you'll have to start in hopes of using it to destroy the dragon from the inside.
To do so, drop down and go to the right to interact with the yellow button. The device will start, but many demons will spawn in the area before you can do anything else, so you'll be forced to kill them all first.
Going Inside the Heart
Once the fight is over, you'll notice that the device works, but you still need to get inside the heart to pierce it manually. To do so, simply follow the path until you get there.
Defeating the Guardian of the Heart
Once inside the heart, you'll encounter your second -and last - boss fight in this game. This time you'll be fighting a creature called the Guardian of the Heart, a mighty boss with four battle phases.
During phase one, your objective will be to shoot the giant eyeballs located on the Guardian's tentacles.
Every now and then, the boss stretches out its tentacles to try and hit you; that'll be your opportunity to shoot the eyeball.
Another attack this boss has during phase one is stretching the tentacle to use it like a whip; you can avoid this attack by jumping over the tentacle.
Phase two starts after lowering around a quarter of the Guardian's health. This time the boss elevates itself, and you'll be able to shoot the eyeballs on its body as well as the bigger ones on its tentacles.
Shooting the smaller ones on the body won't deal significant damage, but they'll drop ammo and health pickups. If you want to keep dealing damage to the creature, aim for the bigger eyeballs.
After shooting all the eyeballs, it's time for phase 3.
During this phase, you'll have to keep shooting eyeballs on the creature's tentacles, but this time you'll be able to use the grappling hook to get around the area and get closer to your targets. Avoid falling as you'll be hit by another set of tentacles moving in a circular motion.
Shoot the eyeballs and get ready for phase 4. During this one, the creature will jump around trying to step on you; you can dash in the opposite direction to avoid getting hit.
Not only that, but the Guardian will try to hit you with its tentacles as well. The creature has a pattern; first, it uses only one tentacle, and then it uses two to sandwich you between them. The boss also uses a circular and a whip-like motion to try and hit you with the tentacles.
Keep an eye out to see when the Guardian is about to stretch out its tentacles, as that'll be your opportunity to shoot the eyeballs. You can also deal damage by shooting the eyeballs on its body.
After that, the boss will enter a new phase; in this phase, he will go back up, and as soon as it goes up, you need to aim to its eyeballs and shoot as many as you can to lower its health. Once the boss' health bar is almost empty, it'll jump, opening a hole in the floor, and you'll fall down.
At the bottom of the hole is a big green puddle; you can use it to bounce back up and get to where the boss is by walking through the obstacles. Once you get closer to the boss, use the grappling hook to finish it.
Killing the dragon will mark the end of this section of the game.