How To Hire a Ninja Maid is the brainchild of Liangnui and entirely too many seasons of Naruto. Originally conceived more as a series of oneshots than as a coherent story, it's essentially designed to answer one question: "What would Yu-Gi-Oh! have been like if Mokuba had actually had a competent bodyguard?" Answer: A lot more surreal than it already was.
After Mokuba's been kidnapped one too many times, Seto decides that something has to change. So, using the suggestions of his recently-rescued younger brother (courtesy of Yugi, of course), Seto decides to get a new bodyguard with entirely different criteria. The candidate must be strong, smart, experienced, and...willing to dress up as the family maid?
What follows is a madcap adventure more in line with what a universe running on card games and crack should really look like—otherwise known as a complete and utter farce. Join Mokuba (the world's only dedicated Seto Kaiba fanboy), Seto (also known as the richest sixteen-year-old ex-psycho supergenius ever), and their newest hires, the deadly ninja Sonozaki Kotone/Akiko (who has all the personality of a brick) and her sister Houjou Setsuna (the resident crazy engineering student and yaoi fangirl) on their journey to thwart kidnappers, ancient Egyptian laser beams, and the starfish-haired Chosen One himself.
Because to do otherwise would be boring.
How To Hire a Ninja Maid includes examples of:
- The Ace: Sonozaki. Or, she would be, since she seems capable of solving every problem with ease. The only problem is that she has functionally no personality of her own and everyone thinks she's the antichrist.
- Black Humor: Mostly coming from Setsuna, but it's not considered a big deal when Jounouchi wonders about the legality of defenestrating Yami Malik. On the airship.
- The Cameo: Various.
- Cerebus Syndrome: Around chapter four, little bits of comedy start bleeding away.
- Chandler's Law: Spoofed.
- Chekhov's Gun: Variously; Seto's brief shock, Kotone/ Akiko and Setsuna's matching accessories (even though they've never met before), Kaiba's secretary's phone call, the fact that both Yami and Sonozaki both see the other as a freak of nature, Hale's comments, the mention of contract magic, and so on.
- Chekhov's Gunman: Hale and Setsuna, at different points in time.
- Cloud Cuckoo Lander: Setsuna can come off as one sometimes to the other characters, mostly because she thinks out loud so much—her sister also has her moments.
- Conflict Killer: Noah is treated as one by the characters. They'd much rather he didn't exist so they could get on with things.
- Deadpan Snarker: Everyone, really. Yami takes the cake, though.
- Enemy Mine: Between Sonozaki and Yami Malik.
- Expy: Two.
- Extreme Doormat: Sonozaki, up until chapter four.
- Gadgeteer Genius: In addition to Seto, Setsuna is also a ludicrously skilled technical engineer. The only difference is that he specializes in electronics and she specializes in mechanics.
- Harmless Villain: Hale.
- Heroic Lineage: Lampshaded a bit and subverted. According to Setsuna, she is descended from a long line of demon-fighting warriors and holy men and women and has inherited exactly one ability. Kotone/ Akiko is also descended from a family of crime bosses and is almost unbelievably strong.
- Highly Visible Ninja: Aside from the opening scene, Sonozaki never bothers with real camouflage.
- Hyper-Competent Sidekick: Sonozaki to Seto.
- Kung-Fu Wizard: The nearest trope to what Sonozaki usually acts as.
- Improvised Weapon: Mokuba, Watanabe, and Sonozaki take out a special ops squad using the contents of the Kaiba mansion's kitchen.
- Lemony Narrator: Doesn't seem to be particularly fond of any of the characters.
- Magi Babble: Do not get the maid started on the technical aspects of magic or different systems thereof.
- Mood-Swinger: Setsuna, which explains why she seems to have so many mutually contradictory tropes to her name.
- Mysterious Past: What, exactly, is up with Kotone/Akiko?
- Ninja Maid: Duh.
- Noodle Implements: In Mokuba's occasional prank wars against staff, he has variously used lubricant, chicken feathers, and household vegetables.
- Noodle Incident: Whatever did happen to Hideyoshi?
- Only Sane Man: Split between Mokuba and Setsuna.
- Otaku: Mokuba. The ninja maid thing was his idea.
- Red Eyes, Take Warning: One of the things in-universe that creeps people out. Naturally, both Kotone/ Akiko and Setsuna have them. Yami also seems to, but it's not commented on as much as his sheer threat level is.
- Shout-Out: To pretty much everything.
- Spanner in the Works: Sonozaki to Malik and Setsuna to Hale. At least once, Malik to Hale as well.
- The Stoic: Seto and Kotone/Akiko.
- Surrounded by Idiots: Hale thinks so, anyway.
- Teen Genius: Seto and Setsuna.
- There Is No Kill Like Overkill: Sonozaki to the Ghouls. In one shot, Malik's original private army was gone.
- Third Line, Some Waiting: There are three plots going on at any one time—Seto and Mokuba versus the canonical plot of Yu-Gi-Oh!, Sonozaki and her mysterious past (and Setsuna), and finally Hale's plots to kidnap and ransom Mokuba.
- Uncanny Family Resemblance: Kotone/ Akiko and her younger sister, Setsuna. They have the same face.
- Wise Beyond Their Years: Setsuna.
- You Gotta Have Blue Hair: In addition to the Yu-Gi-Oh! casts' original hair eccentricity, the resident ninja has blue hair and her sister has green.
- You Have Got to Be Kidding Me!: Setsuna's reaction to nearly everything in the story.