Saintly Church: Played with in Misora's focus chapter after Mahorafest. She pretends to be a kindly old priest in the confessional, but she is actually very mischievious and sometimes downright sneaky.
School Festival: Quite possibly the largest one in fiction. It runs for about a week and takes in several million dollars.
Science Destroys Magic: Side material adds in the interesting fact that the ability to use magic is based on a certain way of thinking the world works, such as the four classical elements. As science advances and disproves these theories, the number of magic users dwindles.
Sealed Evil in a Can: Waking up a legendary demon was the motivation for the villains during the Kansai arc. Also, Eva technically qualifies; although she was sealed less for her evil (which was, if you believe her, considerable) and more because Nagi couldn't get her to leave him alone. Ironically, the protagonists defeat the first abovementioned Sealed Evil by temporarily breaking the seal on the other one.
Serial Escalation: Negi vs. Rakan. Negi reveals that he isn't left-handed at least five times before the match is over, culminating in a spell that definitely deserves the name "Titan Slayer". And Rakan still stands up like nothing happened.
Sex Slave: Averted in the Magical World. Slaves may not have many rights but they are protected from being used as sex slaves.
Sexy Secretary: In Chapter 337, Evangeline tells Chachamaru to become this to Negi as he's working himself to death (apparently enough to literally kill a normal human), even mentioning that she is the only one of the girls who can really help him this way. After confronting him directly about it and telling him that she truly wants to be there to help him, it looks like Chachamaru is in fact going to be Negi's new secretary.
Naturally there is also a hilarious daydream before that where Chachamaru envisioned herself working in this role starting with simple help, moving into what might be several years in the future where they've gotten quite familiar, and ending with Negi insisting on winding up Chachamaru to show his thanks for her help...right before Asakura and Negi himself walk up to her. Cue Did I Just Say That Out Loud?.
Shadow Walker: Teleportation magic works by sending the user through their element in some way. Dark magic uses shadows (as Evangeline demonstrates at the end of the Kyoto Arc).
Evangeline sometimes ships Negi/Chachamaru and derives endless amusement from poor Chachamaru's plight, though deep down she really is quite supportive.
Ship Sinking: In chapter 353, Negi tells Asuna that he likes someone. The reaction makes it clear that it's not her. Two chapters later, Nodoka and Yue's ships are sunk, Chisame's ship is sunk and Evangeline's ship is sunk. Even Makie's appears to be sunk. Yes, Akamatsu went out of his way to sink the four or five most popular ships, and Makie's, without saying who he did like. So... any Chachamaru fans out there? Akira?
Shown Their Work: Shown mainly in the compiled volume extras and magazines, which give descriptions on both in-universe physics and real world data, such as the use of surprisingly good Latin... And Greek. And Sanskrit. Other examples are the Hakkyokuken, Negi and Ku-Fei's martial arts style and the physics behind Negi's Raisoku Shundo. And the geography of Mundus Magicus, which appears to be Mars with oceans — which is finally pointed out by one of the characters in a July 2009 installment. And Chisame's battle against a TCP tuna swarm; she repels it setting up a bucket filter, even using the correct sentence to implement it in iptables!
Single Woman Seeks Good Man: Most of the girls who have a crush on Negi fall under this. Negi himself is a very kind, caring, protective boy, and most of the time the girls initially fall for him because they see that kindness as they become friends with him or he helps them out.
Sneezing: Negi used to be affected by frequent bouts of clothing shredding sneezes in the early volumes of the manga. The sneezing decreased when the story grew more serious, the Fanservice didn't: Notably, sneezing mostly occurs in the downtime between major, action-filled arcs.
Nearly literal when Eva strands Asuna on a blizzard-wracked mountain as part of her training. Asuna freezes solid while sleeping, then wakes up dead. Ask any doctor. Being Asuna, however, this is not sufficient to keep her down. Evangeline later hits her with an insta-kill freeze spell; once again this is insufficient, although in this case her ability to cancel magic may have helped. She was still stuck in an ice crystal long enough to suffocate.
Sorting Algorithm of Evil: Subverted, as Negi fights Fate, one of the most powerful ennemies of the series, very early-on in the Kyoto arc; but he doesn't reappear until the Magic World arc, 14 volumes later. The series follows the algorithm otherwise.
Stable Time Loop: The three days of Mahorafest. Done inconsistently, though: Their week-long jump back does end up changing the past, but it ends up being stable due to it being consistent with Chao's timeline. Basically it's a sort of destiny thing, otherwise there would be like a huge paradox, and if they hadn't succeeded, Chao would never come back in time to do it.
Superpower Lottery: Pactios act as this, giving a artifact with a different ability depending the individual's personality. Some are good for fighting, some are stuff outside of fighting. During Negi's fight with Rakan, he entered a pactio that allowed him to use the artifacts of anybody he entered a pactio with, which he canceled after the fight.
Super Speed: Raiten Taisou. Koyomi's artifact ability. Also one of the effects of Ako'sartifact.
Synchronization: Haruna's golems have a slight version of this since when one is used to defend from an actual attack, it gives her a Psychic Nosebleed and knocks her out but doesn't pass on the full damage from the attack.
After the group realizes that the Asuna with the group might be a fake, Tatsumiya attempts to unmask the impostor using a magic bullet. Negi, however, doesn't want to see her hurt, impostor or not. Faced with the option of either allowing a spy to run free or hurting a real Asuna (despite assurances from Tatsumiya that the bullet would be harmless in this case), he instead forms a Pactio with the impostor, with the added side-effect of stripping away the disguise.
Both Cosmo Entelecheia (the secret society/terrorist group) and Zazie's sister believe that the inhabitants of Mundus Magicus must either be sealed in Cosmo Entelecheia (the Lotus-Eater Machine) or die/end up in a desperate war with Earth when their home dimension inevitably collapses. Chao Lingshen tried (or claimed to be trying) to reveal magic to the inhabitants of Earth at large so as to make the latter option less disastrous, given that the former apparently didn't happen. Negi, on the other hand, has an idea to prevent the collapse.
Teacher/Student Romance: The entire idea is lampshaded and deconstructed on multiple occasions. Negi constantly worries about maintaining a normal student-teacher relationship with all the girls of his class while several of them keep developing crushes on him.
Tempting Fate: Ayaka says that she has a bad feeling about going to the Magic World and Asuna claims that Ayaka's premonitions are usually wrong. Guess what happens to Ala Alba.
Terraform: Negi's ultimate plan to save the Magic World as revealed in Chapter 338. His theory: Magic/Mana is fueled by life, and because Mars as it is is a dead world, it's the main reason for the ultimate collapse of the Magic World. By Terraforming Mars and making it Earth-like, the Magic world can eventually thrive there without problems. The immense size and cost of this project is also why Ayaka and Chizuru are now sponsoring it. Also, given how long it would take (Negi estimates between 30 and 100 years), it explains how busy Negi's become and how it could be a "lifetime" project.
Subverted early on, however, when Negi gets cheered up by Satsuki during Mahorafest.
There Is Only One Bed: Weirdly inverted — the girls understand and accept that no matter how many beds are present, Negi is likely to crawl into one a girl is already occupying. (Especially Asuna.) They even turn it into a game of Keep Away on one occasion, fighting over who gets him. The one girl who doesn't want him there, of course. Of course, it's debatable whether she still doesn't...
Time Skip: In chapter 350, five months have passed from the "Get Negi to confess" to "Asuna's 'graduation'" seeing as she's going to be sealed again at Mars.
And then again in chapter 352, 130 years have passed, as Asuna wakes up late in a future world to find all of the plans succeeded... and to find that Negi has apparently somehow died, in addition to all of her old classmates with the exceptions of Chao and Eva, who bring Asuna back to the original timeline next chapter.
And once again in chapter 354, this time 7 years after the original timeline, by which all the girls of Class 3A have long graduated, as shown by Yue who now works as a private investigator involving magical cases. This also introduces a few new characters, such as Maki's younger brother Kagehisa, who by this time is in high school.
To Be Lawful or Good: Negi gets this from time to time, having to choose when to break laws and when to let things slide, often while under threat. He's fairly flexible, coming down on both sides depending on the severity of the issue.
Token Yuri Girls: Setsuna serves as Konoka's protector, and admits it precludes hooking up with anyone else. Naturally, other characters assume this is a complicated way of saying that they are a romantic couple, or will be. Konoka certainly has no problem being her partner in their (kissing-activated) magical contract. It's pretty much just Setsuna who isn't aware of this. Naturally, when Setsuna proved to be a popular character, the overtones became a lot more obvious in the Negima?! remake, with a more knowingly teasing Konoka and a more flusterable Setsuna, to the point of Setsuna stuck between embarrassment and ogling at Konoka in a swimsuit. Considering that in the early manga the way Setsuna acts around Konoka is exactly the same as someone with a really strong crush (complete with blushing and a loss of the ability to speak whenever she's around) makes the subtext already quite strong.
Took a Level in Badass: Pretty much automatic if someone gets an artifact. This includes Negi, though overshadowed by the fact that he had just gained about eight others. Maybe, his artifact could be a Game Breaker because he has so many attendants, he can use all their powers, granted, one at a time, but still it gives him a lot more options than almost anyone. Has been Put on a Bus for a while now.
Yue is arguably the queen of this trope, having done this no less than three times. See her character entry for details.
Yue's best friend Nodoka is the goddess of this trope.
Took a Level in Jerkass: The class actually attacks Negi near the end of the manga in order to find out who he likes including using their pactios against him, removing his allies from the area and attempted to mind control him via Chizuru. Why? Because he was busy saving billions of lives instead of responding to their romantic interest. Notably, a few of the girls like Chisame do have better intentions, but most do not while only Chachamaru, Asuna, Akira and Satsuki are actually decent enough to stand by him.
Too Much Information: Asuna gets an earful from Makie during the shower scene: "Negi-kun's you-know-what is touching my you-know-where! ... His you-know-what's getting you-know-what-er!"
Total Party Kill: Discussed a few times after they entered the magical world arc as with so many other game tropes, especially when they were separated.
Touch Telepathy: Negi Springfield is shown to have this ability via placing his hand on the forehead in the first chapter, though he can only catch a few thoughts at the most.
Jack Rakan later gets to see a Flash Back from a defeated enemy he's holding.
This is one of the abilities of Shiori's race, which is why she ended up the Last Of Her Kind.
Lampshaded with Ku Fei's martial arts training, as her trying to create a "quick-powerup" training regimen for Negi based on old manga and kung fu movies fails miserably. She then tries training him conventionally, which works, and teaches him so quickly that she gets depressed about it.
Played straight, however, with Evangeline's training methods, which actually seem to work.
Translation Convention: Scenes that take place in Britain are spoken in Japanese. The girls, even the ordinary ones, also have no trouble in the magical world — averted though, in that it was colonized from Earth (Mundus Vetus, "the Old World"), and two of its major languages are "Anglicum" and "Japonense." Interestingly, though, the writing dotted around the Mundus Magicus suggest that the lingua franca is actually Latin.
Translation Style Choices: Most fan translations fall into Category 2 or Category 3, while the former official translation was a solid Category 2.
Truer To The Text: An interesting case. The recent OVA releases have been faithful to the manga, but they're so deep into a story that none of its multiple previous adaptations properly covered, that they won't make much sense to anyone who hasn't read the manga.
Two Scenes, One Dialogue: Variation: just as Fate finishes explaining the secret of the Magical World to the captive Asuna and Anya, the next chapter begins with Shiori/Luna confirming the same explanation for Negi and company.
Unlimited Wardrobe: When the girls are not attending class, and wearing the Mahora uniform, they each have fair amount of unique casual clothes. It's obvious reading the manga, that Akamatsu and company spent a lot of time coming up with fun looks for all of the girls.
The Unmasqued World: Negi and friends pay a brief visit to a "bad" future in which the current antagonist has recently succeeded in revealing the existence of magic, but aside from the excited attentions of some local girls and talk of all mages being recalled to the Magic World, we don't see much of the effects. Magic is revealed for good off-screen during the final timeskip, and more integration between the worlds (including black market trade) is discussed.
The Unreveal: 355 chapters and we never learn who Negi actually likes or ends up with. He does tell Asuna at one point, but the audience doesn't get to hear it, and her reaction doesn't make it clear who it is- except it doesn't seem to be her.
The Unwanted Harem: Double Subversion: the professor surrounded by 31 female students sure looks like a set up for one of these, but, while the students may find Negi cute, they don't want to go out with him. Except, of course, that several of them do develop romantic feelings for Negi, though nowhere near as much as the premise would lead you to believe.
Justified in that they develop romantic feelings for him after he shows how mature, badass or awesome he is, and most of them look at him and realize that the ten year old kid will turn into the epitome of sexy and badass in five years tops.