WARNING: The following contains major spoilers for Teenage Mutant Ninja Turtles: The Last Ronin #4, available now from IDW.

The world of The Last Ronin (by Kevin Eastman, Peter Laird, Tom Waltz, Ben Bishop, Esau Escorza, and Isaac Escorza) has set out a dark future for the Teenage Mutant Ninja Turtles. While the Foot Clan rules over the remains of New York City, an aged, grizzled Michelangelo nurses his wounds in the company of the only old friend he has left, April O'Neil, until they are ready to launch another strike against the villains who have taken over. It's a minor setback, but also the perfect opportunity for the last of the Ninja Turtles to catch up on everything he's missed during his time away. Unfortunately, that includes the startling revelation that Michelangelo and his brothers are the reason April O'Neil and Casey Jones' daughter is something more than human.

After being sorely defeated by the Foot Clan's mechanized forces and left for dead, Michelangelo was narrowly rescued by Casey Jones, the daughter of April who is named after her father. Just like her parents, Casey has also been preparing for the battle at hand. Mikey comes across her training in the Turtles' old lair and, after a short sparring session, offers to refine her objectively poor fighting style. It's a heartwarming moment, especially to April who overheard enough of it to be moved by Michelangelo's offer. However, their ensuing conversation reveals that Casey is also a mutant.

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When he realizes the truth, Michelangelo asks April when she was planning on telling him the truth about her daughter. He questions April about injecting Casey with Mutagen, but the reporter denies having ever done so. According to April, all manner of tests were run to determine how her child could have ended up with super strength and a mutant healing factor, but none of them were conclusive. As best she can guess, her and the original Casey Jones' lifelong exposure to the Turtles likely left them with trace amounts of Mutagen in their DNA, which was passed along to their daughter.

While the TMNT universe is one full of extraordinary concepts, this still doesn't sound very likely. Something similar isn't unheard of, however, as the former Foot assassin Jennika was transformed into a Turtle through a life saving blood transfusion from one of them. Even taking that into account, general exposure to mutants doesn't seem like enough to cause a human to give birth to a mutant child. Taking everything that is already going on into account, the specifics of this situation don't really matter much at the moment, and the two decide to table the matter for the time being.

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April and Michelangelo might be able to keep Casey's origin a secret for now, but there is no telling how long they will be able to keep up the ruse.

The war against the Oroku Hiroto and the Foot Clan is a great distraction, as well as a great way for Casey's powers to come roiling full throttle to the surface. When that happens, it's going to be hard to deny the fact that she is more than human.

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