Hamato Hisako is an extraordinary girl with extraordinary powers. More than that, she had the greatest family she could ask for, The TMNTs. However, their lives are far from easy, especially when a bunch of baddies are trying to figure out the Secrets of the Sewers.
TMNT: Secrets of the Sewers provides examples of:
- Adaptational Jerkass: While Stockman has always been a bad guy in all TMNT media, this incarnation is arguably the nastiest and least sympathetic version of him. He readily and eagerly performs inhumane experiments on humans and mutants alike, children included, and is perfectly fine with subjecting them to Cold-Blooded Torture on a whim.
- An Arm and a Leg: Shredder has his arm torn off, and it's later replaced by a prosthesis.
- Avenging the Villain: A variation occurs later in the fic. When the Shredder is presumed dead, the Foot High Council take it upon themselves to fight the Turtles and Splinter to avenge his death... but they're only doing so because Shredder's twisted things around to make himself look like an honorable man and Splinter a despicable traitor. They back down once they realize their error.
- Became Their Own Antithesis: As revealed in chapter 23, Oroku Saki began as an honorable Nice Guy who defied orders during a mission to rescue Tang Shen from a yakuza group, stating that he can't let innocent people suffer and is disgusted by the yakuza treating human life like "something to be bartered and sold." Come the present day, as the Shredder, Saki's become everything he's hated about the yakuza and more, allowing Stockman to perform inhumane experiments on humans and mutants alike, including children, to amass an army for himself.
- Bluff the Imposter: When some Purple Dragons disguised as cops come to the pizza place where Casey works, asking questions about Hisako and making her out to be a criminal, A suspicious Casey asks them about another cop, his father (not giving his own last name) who died in action years ago. When they reply as if he's still alive, he knows that they're fakes.
- Broken Bird: Hisako, due to her Dark and Troubled Past does her best to be strong in front of her family. Her facade falters when exposed to certain triggers.
- Broken Pedestal: The reveal of how twisted Stockman really was affects April so much that she changes the focus of her studies from science to journalism to make sure that monsters like him get what they deserve.
- realizing that he stole her from her true father and tried to brainwash her into hating him causes Karai/Miwa to lose any love for Shredder pretty quickly.
- Bullying a Dragon: Stockman when he tortures Hisako's family and tries to slit Mikey's throat right in front of her. He's lucky she showed mercy and just wiped his memory
- Horrible Judge of Character: The High Council of the Foot Clan are convinced that the Shredder is an honorable, righteous man and that Splinter is a despicable, dishonorable monster when the opposite is the case; in fact, it's revealed in the very next chapter that everything Shredder has done throughout the fic has been to amass an army of mutants so he can slay the council and take complete control over the Foot. They nearly kill Splinter to avenge Shredder's apparent death, and would have done so had Murakami not intervened and helped set them straight.
- Identity Amnesia: Hisako extracts and destroys all of Stockman's memories, rendering him completely unaware of who he is.
- She later tries to the same to Karai, and though the Shredder interrupts her, the glimpse of Karai's memories allows her to realize that Karai and Miwa are the same person.
- Poor Communication Kills: The Foot leadership's belief that Shredder is a good person nearly gets Splinter killed before they can clear things up.
- The Starscream: The Shredder's plan was to build an army to take over the Foot.
- Trauma Button: Hisako has multiple triggers, including the smell of antiseptics or someone saying TCRI or Baxter Stockman
- Villain Team-Up: Shredder, Tiger Claw, and Kraang team up to get revenge on the Turtles.
- Villain with Good Publicity: Another example with Stockman. In his day job, he's the respected head of TCRI with 18 patents and 5 PhDs, with no one suspecting he's a psychotic mad scientist. Proven when the Turtles tell April what he's really like and she refuses to believe it until she sees the evidence with her own eyes.