Massive Multiplayer Crossover / Anime & Manga

• The Giant Robo OVA series featured characters taken from several other series Misuteru Yokoyama — the original creator of Giant Robo/Johnny Sokko and His Flying Robot — had written. This included adaptations of the medieval Chinese stories Romance Of The Three Kingdoms and The Water Margins, which led to many main and secondary characters in ancient Chinese clothing coexisting with people in three-piece suits 20 Minutes into the Future. It also included the very first Magical Girl, Sally the Witch, under her original name "Sunny", as Shockwave Alberto's daughter.
• Legendary Manga creator Osamu Tezuka similarly uses Reused Character Designs in his "Star System", wherein a character from a previous work will actually play a different role in another story, as if they were an actor or actress.
• DragonFall◊ blended Dragon Ball, Star Wars and a whole bunch of other series into a parody. With mixed results.
• The intro to the Rumiko Takahashi gallery show It's a Rumic World explicitly crosses over Ranma ½, Urusei Yatsura, and Inuyasha.
• Tsubasa -RESERVoir CHRoNiCLE- has the characters jumping from Alternate Universe to Alternate Universe filled with CLAMP characters from their various series.
  • Amusingly, save a select few examples, mostly as cameos, the Alternate Universes are hardly ever populated by actual CLAMP characters, but Alternate Universe instances of them.
  • Their first crossover happened in Clamp Campus Detectives since the three main character were in series/stories on their own before CCD: Nokoru Imonoyama in Duklyon, Akira Ijuin in 20 Mask ni Onegai (Man of Twenty Masks) and supposedly Suou Takamura showed up in an old oneshot. Then there was X/1999 where characters from past CLAMP series started appearing, including Subaru, the main character of Tokyo Babylon, as a major character, and during his series set in the early 90s it was said that he would have a role in End of the World as We Know It that is X, making for a bit of foreshadowing.
• Shattered Angels is primarily a crossover of the mangaka and studio's previous works: Destiny of the Shrine Maiden, Steel Angel Kurumi, Magical Meow Meow Taruto, and UFO Princess Valkyrie.
• Before Dengeki Gakuen RPG: Cross of Venus (mentioned below), there was this animated short produced for Dengeki Bunko's 2007 Movie Festival, featuring chibi versions of characters from Kino's Journey, Inukami! and Shakugan no Shana (Note that the chibi Shana here is not Shana-tan; for one, she is the stalker rather than said omake series' Kazumi.).
• While most Go Nagai series contain cameos here and there, the recent Shin Mazinger seems to be going the whole way. Characters from several alternate versions of Mazinger Z have shown up, as well as characters from Violence Jack (itself, a Deconstruction Crossover) and the titular demon from Demon Lord Dante. Unsurprisingly, this series is being directed by the same man behind Giant Robo, Yasuhiro Imagawa.
  • CB Chara Go Nagai World is a crossover which features SD versions of Mazinger Z, Devilman, and Violence Jack, with in-story explanations for the characters being SD, and with plenty cameos (such like UFO Robo Grendizer, Kotetsu Jeeg and Getter Robo).
  • Go Nagai has been doing this for a loooong while. Back in the seventies several movies were made by Toei crossing Mazinger Z with Devilman, Great Mazinger with Getter Robo and Getter Robo G or UFO Robo Grendizer, or several of them together.
  • Super Robot Retsuden, with story and art by Ken Ishikawa, is an Affectionate Parody of those movies. Mazinger Z, Great Mazinger, UFO Robo Grendizer, Getter Robo and Kotetsu Jeeg characters join their forces to face an Eldritch Abomination.
  • And the Dynamic Heroes e-manga is a Crossover featuring Mazinger Z, Great Mazinger, UFO Robo Grendizer, Getter Robo, Getter Robo G, Devilman AND Cutey Honey.
• The Pretty Cure All Stars movie series allows the Cures from the past seasons to meet (and be friends with) the new team.
• About a week after the debut of the film Dragon Ball Z: Battle of Gods, Goku and his friends turned up in the latest annual One Piece and Toriko crossover episode.
• Kazuma Kamachi will write a light novel that crosses over all his works called A Certain Magical Heavy Zashiki-Warashi Deals With a Simple Killer Princess' Marriage Circumstances.

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