And now that Magic itself is becoming So Last Season in Force, the only appropriate words left in the title of that series is "Force" and "Record"!
In Dragon Ball, while the title plot coupons are the driving force of the first series, as time goes on, the show becomes less about the aforementioned Dragon Balls and more about watching long-winded bouts between various superhuman beings. By Dragon Ball Z, the balls are relegated to little more than a plot device the protagonists customarily fall back on when too many of their own die. This comes full circle in the follow-up anime series Dragon Ball GT, where the Dragon Balls are the central focus again.
This is even lampshaded after all the Dragon Balls have been gathered the first time, Shenron made his appearance and the Balls were lost again.
A version appears in Fist of the North Star, although it's not the title of the series. Kenshiro's signature attack is the "Hundred Crack Fist of the North Star". But why "Hundred Crack?" Because in its first published appearance in a non-canonical prequel pilot, the move's entire purpose was to crack an enemy's hardened armor in a hundred places. Thus, it is the "hundred crack" fist. However, it was never used for this purpose in the main series, instead just making enemies explode like everybody else.
In the first chapter of Record of a Yokohama Shopping Trip Alpha does indeed taking a shopping trip to Yokohama—which has no actual relevance to the rest of the series until the very last chapter, when she goes shopping again.
Only the first few chapters of High School Of The Dead are set in a High School. This is, however, mostly the result of a translation issue. A more accurate translation of the title is "Academy Apocalypse", which makes slightly more sense.
Index, the title character of A Certain Magical Index, gets Demoted to Extra within the first ten episodes. Although the occasional arc gives her more focus, she never regains the importance she had in the first arc, making her little more than another Girl of the Week in that respect. However, given that she lives with Touma and played a rather important role in the WWIII arc, she has fared better than the likes of the true C list fodder of the cast.
Elfen Lied is named after a German song of the same name, which was featured throughout the manga. The anime, however, dropped the song and left the name.
"Elfen Lied" specifically translates as "Elven Song".
Yu-Gi-Oh! 5D's was about five Signer Dragons... until Crow's Black-Winged Dragon came along.
The "Yu-Gi-Oh!" itself is an artifact; it means King of Games, and is the title because its main character (or rather, the main character's alter-ego) is invincible in any game. After Duel Monsters became the only game anyone played (from volume 8 of the manga on), the title started to make less sense. And the person titled "King of Games" isn't even present in the various spinoffs, having moved on to the afterlife at the end of the original series.
Not exactly from volume 8 on. The Shadow RPG, Four Aces, and Dungeons Dragons & Dice weren't Duel Monsters. So one can say it only applies to the anime and its spin-offs. Granted, DDD showed up as DDM (Dungeon Dice Monsters) in the anime and so did the Shadow RPG, but in the anime they rewrote the DDD arc with Duel Monsters in mind and the tabletop aspect of the Shadow RPG was radically nerfed in favor of additional card battles and other anime-related changes.
Axis Powers Hetalia is beginning to lean this way, with very little of the new material focusing on WWII or even on Italy. This may be part of the reason the anime was renamed to Hetalia: World Series and later Hetalia: It's a Beautiful World, although the "World 8" are still used as "main characters" in anime marketing.
Saint Seiya got that title because Seiya was The Protagonist but new sagas don't even have him as a character, as they revolve around different Athena's saints, sometimes a century apart.
Guru Guru Pon Chan. The "Guru Guru" in the title refers to spinning, and only in volume 1 did Ponta spin to transform.
The anime adaption of the Haruhi Suzumiya light novels gets its title from the first novel, The Melancholy Of Haruhi Suzumiya; however, the show adapts from 5 different books, each one with a different title. Currently it has adapted the first three books plus some short stories of the fifth and sixth novels.
Averted by The Movie based on the fourth novel, since it's named after the book.
Marmalade Boy got this twice: the original title referred to The Protagonist as that would be a guy before the author decided to do a Gender Flip and got a female protagonist instead, though the manga subverts this by having said protagonist nickname her Love Interest after marmalade in a Title Drop. Furthermore, in Spain the anime was renamed "La Familia Crece", which means "The Family Grows" and refers to the first episode setting up the two families living together, though this isn't given a lot of attention during most of the show. There's even barely any Flirty Stepsiblings angst or the like.
Medaka Box: The box in the title plays less and less of a role as the series goes on. Initially, its role made sense as the series revolved around helping others with their day-to-day problems. Now, it's only occasionally used as a plot device.
Pandora Hearts takes its title from author Mochizuki Jun's debut oneshot, where a "Pandora" is a box that resides in the chest of anyone who contracts with an "abyss." In the series proper, the box is replaced with the incuse that appears on the chests of illegal contractors, "abysses" are now known as "chains," the Abyss is the name of the Eldritch Location where chains are born, and Pandora is the name of the organization that researches the Abyss.
The gag manga Tensai Bakabon is initially about a comically stupid little boy named Bakabon and his adventures with his pals, focusing so strongly on his point of view that his parents don't even get names, referred to only as "Papa" and "Mama." Over time, however, Bakabon's troublemaking father proves to be a much more popular character, to the point that the series soon revolves around him and his various schemes. Bakabon himself is demoted to his occasional sidekick. Despite this, the dad is still never given a name, and is called "Bakabon's Father" on merchandise.
YuYu Hakusho translates as "Ghost Files," and this reflects the actual stories at first; Yusuke, as a ghost, helps other ghosts. Before too long, it morphs into a fighting series similar to Dragon Ball Z.
Only the first fourteen episodes of Sword Art Online are actually set in the eponymous video game, after which it's destroyed. Experiences and technologies from SAO do serve as plot points from time to time, though, and on a more basic level swords, skill with swords, and online games are important through the whole thing.