Some TMNT stuff really isn't for little kids.
Inside Out is a five-part story that was first published as a backup series to the first five issues of Teenage Mutant Ninja Turtles Universe.
- Story: Kevin Eastman, Bobby Curnow, Tom Waltz
- Script: Tom Waltz
- Layouts: Kevin Eastman
- Artist: Bill Sienkiewicz
- Colorist: Tomi Varga
Leonardo follows a shadowy ninja over thirteen city blocks before finally pouncing on him, only to discover the enemy ninja is not alone. He handles them all with ease, talking all the while, before being shocked by the arrival of a Four-Armed Mutant Foot Ninja. He finds himself more taxed by this foe, and chops off one of the ninja's arms before impaling him on a pipe. A few more ninja appear and are easily dispatched, but Leonardo finds himself facing an ambush: a row of bowmen aiming at him. He flees, with arrows all around him.
Leo makes his way to the park, still pursued by dozens of arrows, and hides among the trees. But instead of ninjas, he's confronted by grinning trees and blobs of earth shaped like Utroms. The ground under him becomes swampy, and he finds himself looking up at the farm in Northampton, where he's attacked by tentacles and the water itself. Koya emerges from the water, screaming that she wants revenge, and Leonardo tries to lead her back to the woods so she will have difficulty flying. He makes his way into a storm drain, and challenges Koya to come after him.
But instead of Koya, Leo's suddenly swarmed by rats, which he manages to throw off of his body. But the Rat King has also brought a trio of Shredder Clones, and Leonardo fights the three while declaring that this isn't the Rat King's world, but his own. He changes his surroundings from a sewer to a cavernous stone building, where he demands to know what's next. Suddenly a dragon appears, declaring that he is Leonardo's destiny: "the future that burns." Leonardo avoids the dragon's fire by leaping into a pool of water.
Leo emerges in Harold Lillja's laboratory, where the teleporter is activated. Harold screams at him that he told him the Turtles are not welcome, and commands Metalhead to kill Leonardo, only for Leonardo to electrocute the robot with a handy cable. However, this somehow makes Metalhead stronger, and he begins drawing more machinery to himself, merging with both Harold and the Fugitoid into a giant, monstrous robot. Leonardo is hard-pressed, barely able to avoid the robot's fists.
Suddenly Leo finds himself on a street, with Casey Jones shouting down from a rooftop, saying that Leonardo's control belongs to the "real you" that doesn't "hide behind a mask." Just then, another Leonardo appears—the brainwashed dark one from City Fall—and begins fighting him. Just as Leonardo is starting to doubt himself, Tang Shen appears to reassure him, telling him that he should not succumb to darkness and fear, and that he was born to be a warrior and a leader. With a final burst of energy, Leonardo defeats his darker self.
Just then, Leonardo awakens in the lotus position, having been dreaming the whole time. April expresses relief that he's back, and Leonardo reveals that the key to all he's seen is fear—it's used by Kitsune and the Rat King, but it can be overcome by remembering who you truly are. "Now I stand. Now I lead," he declares.