Sequels and spin-offs are a common occurrence in the anime industry, either to expand on the source material or to simply capitalize on a series' raging popularity. Most sequels are heavily marketed to draw in newer viewers and entice the franchise's already loyal fanbase. However, a few have been swept under the radar, with fans unaware of the actual roots of these series.
It's rather uncommon for sequels or spin-offs to go undetected, with similar names being the obvious giveaway. Still, it's quite plausible in the case of spin-offs based on much older series or sequels with differing names, making these entries a surprising revelation. Moreover, some authors prefer to keep their manga as standalone series, despite being set in the same universe.
6 Yashahime: Princess Half-Demon
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Only true fans of the franchise would know that the recently aired Yashahime: Princess Half-Demon is actually a sequel to the famed Inuyasha series. The original hit shojo anime centered itself around the adventures of Kagome, a girl teleported back in time from present-day Japan, and a half-human boy named Inuyasha.
The sequel focuses on the next generation, with the story following Moroha, Inuyasha and Kagome's daughter, and her companions' adventures through the two differing timelines. With a distinct name, many fail to recognize this shonen series as a sequel to the original shojo action anime.
5 Sailor Moon
Many remember the 90s' most popular shojo series as an original adaptation and the first of its kind. However, Naoko Takeuchi's manga Codename: Sailor V predates the first Sailor Moon manga, technically making the latter a sequel of sorts.
Fans of the franchise might not be aware of this fact due to Sailor V never being adapted into an anime. An OVA for the manga was set to air sometime before Sailor Moon's launch, though it never actually aired. While not a direct sequel, the Sailor Moon series is still a continued storyline, making it a sequel of sorts.
4 Yu-Gi-Oh!
From novice watchers to anime veterans, Yu-Gi-Oh! is a household name that has defined the card game genre. Being a pioneer of battle-card anime, many assume that the series is the first adaptation of its franchise. However, the show is actually predated by a distinct adaptation of the manga that has now been dubbed by fans as Yu-Gi-Oh! Season Zero.
Season Zero followed an entirely different narrative from what the franchise is known for today, delving into everything but the concept of card battles. The adaptation eventually tanked, with producers devising a new rendition of the manga, one that became a legendary success. Season Zero was swept under the rug, with the series eventually being lost to time.
3 Paradise Kiss
Paradise Kiss is a standalone anime adaptation based on Ai Yazawa’s manga of the same name. The series centers itself around Yukari, a typical high school girl who somehow ends up being scouted by a high-end fashion brand known as Paradise Kiss. While the author intended for the adaptation to be a standalone series, the anime is actually a sequel to another one of Yazawa’s works known as Neighborhood Stories.
Neighborhood Stories features some of the same characters as Paradise Kiss, with the premise also revolving around a fashion brand. However, the focal characters of the two series differ and the plot tends to move in different directions, leading to Paradise Kiss being denoted as a standalone series instead of a sequel. Still, the timelines align and some of the same characters can be seen in both shows, technically making it a sequel.
2 Higurashi When They Cry – GOU
The original Higurashi When They Cry has made a name for itself in the anime industry's horror landscape. Brimming with twists and turns, the show was able to turn heads with its gut-wrenching plotlines and horror-imbued thematics. In 2020, a remake of the anime adaptation was announced with the title Higurashi When They Cry – New.
By the second episode, viewers were taken by surprise by a rattling twist as the series' title was reframed to Higurashi When They Cry – GOU, revealing that the new adaptation is actually a sequel laden with time-travel twists. With the initial buzz of the new adaptation serving as a remake, many fans of the franchise were never acquainted with its true nature of being a murder mystery sequel.
1 Great Teacher Onizuka
Most recall Onizuka as a teacher with a (somewhat) professional attitude, loved and adored by all for his charming antics. However, Great Teacher Onizuka's true beginnings are actually set in juvenility and delinquency. The series is a sequel to Shonan Junai Gumi, centered around the Oni-Baku duo compromising Eikichi Onizuka and Ryuji Danma.
Shonan Junai Gumi's narrative is rather absurd as the two main characters are on a quest to lose their virginity. However, the very same absurdity depicts Onizuka's growth from a deviant high schooler to a sophisticated teacher. Although, fans of Great Teacher Onizuka might have a hard time watching their favorite teacher in such a crude character.