Digimon holds a special place in the hearts of many anime fans, especially those who grew up during the late 90s and early 2000s. While the franchise never quite reached the same commercial heights as Pokémon, an argument can definitely be made that Digimon's anime far exceeds Ash's neverending adventure to catch 'em all.
If nothing else, Digimon Adventure sought to tell a complete story, even if not every plotline received a proper conclusion. The subsequent sequels mainly did their own thing, with only a handful of references to early entries. While not all seasons are great - looking at you, Savers - Digimon knows how to keep things interesting. Consequently, a couple of intriguing storylines wound up lost in the shuffle.
Leomon's Fairy Tale
Leomon is arguably one of the most beloved Digimon of all time. Just look at that spectacular beast! Seriously, Leomon was made to be trusted. While those stunning blonde locks and impeccable abs may seem reliable, Leomon's words are better taken with a grain of salt.
Digimon is more fantasy than anything, therefore prophecies crop up quite often. Unfortunately, they tend to not amount to much. Early on in Digimon Adventure, Leomon tells the heroes about a prophecy proclaiming the arrival of seven DigiDestined. Only, with the eventual appearance of Kari, there are actually eight DigiDestined. So, what does this spell for the earlier prophecy? Does this suggest that destiny is shaped by the participants? Does this twist support the concept of free will in the Digital World? Where the writers just making it up as they go along and decided to throw Kari into the equation? Who knows!
The Wall Of Fire
Digimon has an annoying habit of bringing up fascinating concepts that are largely left unexplained. Adventure 02 is slightly more notorious in this regard, but the original anime is hardly faultless. Apocalymon is Adventure's big bad, a being born from the Digimon who perished while trying to digivolve.
Where does Apocalymon come from, exactly? Well, he hails from beyond the Wall of Fire. What is the Wall of Fire? It is an unexplainable phenomenon that exists solely to hinder Apocalymon's process. Who created it? No clue. Why can't Apocalymon pass? Nobody knows. There must be something more to this concept than just a plot device to stall Apocalymon until the DigiDestined are strong enough to mount a challenge.
What Is Etemon's Deal?
Admittedly, this is less of an incomplete storyline and more of a big gaping omission. Etemon is the second main villain faced by the DigiDestined, with the Elvis impersonator lasting for a solid six-episode arc. Etemon is definitely entertaining, but the villain has no defined motive in the series.
Digimon Adventure's antagonists are not exactly complex, but they usually have some goal besides being an obstacle for the heroes to overcome. For example, Devimon wanted to take down the DigiDestined to stop a prophecy proclaiming his defeat at the hands of T.K. Etemon merely exists.
The Mystical DigiDestined
Towards the end of Digimon Adventure, it is revealed that Tai' and co. were not actually the first "chosen" DigiDestined; in fact, five kids had previously saved the Digital World from the threat of the Dark Masters. Putting aside the fact that that the anime tried to pass silhouettes of Adventure's heroes as the designs of the original DigiDestined, very little is actually revealed about this group of children.
Digimon Adventure tri. does introduce two of the DigiDestined, but the other three are left unnamed. While their adventure was not all that pertinent to Tai, Matt, and company's quest to save the Digital World, it would have been nice to learn a bit more about the original DigiDestined.
A Prophecy Out Of Nowhere
This is less of a dropped storyline and more of a plot point that comes completely out of nowhere and highlights the fact that Digimon Adventure was largely created on the fly. After Myotismon is defeated, Izzy receives an email about a prophecy announcing the arrival of the Undead King's Beast form.
As nothing set up about Digivolutions permits Myotismon to transform into his Mega form, this prophecy is thrown out to justify VenomMyotismon's appearance. If Digivolutions can be triggered by incorporating data of other Digimon, then VenomMyotismon's existence raises a lot of questions.
Kazu & Kenta: Behind Bars
Digimon Tamers is the darkest entry in the series, with the exception of perhaps Tri. Jeri's depression arc is surprisingly effective, while the main heroes largely avoid coming across as copies of Tai, Matt, and Sora. In Tamers' action-packed finale, the heroes are trying to stop a man-made weapon called the D-Reaper from wreaking havoc in the Digital and Real Worlds.
Throughout all this chaos, Kenta and Kazu are suddenly surrounded and taken away by the police. As this happens in the final episode, we never see them again. While they were presumably just returned to their parents, it ends their stories on an odd note.
Gabumon Is Recognized By Matt's Dad
Next up, an English dub exclusive that mostly succeeded in fueling fan theories. During the Myotismon arc, Matt's dad reveals that he knows about Gabumon. This is an odd turn of events, as nothing suggests adults even know about the existence of the Digital World. This one line led to a ton of questions.
Well, it was pointless. In the Japanese version, Hiroaki Ishida says something completely different. This moment is basically a red herring masquerading as a potential storyline.
Hello Dark Ocean, Goodbye Dark Ocean
Here is the big one! The Dark Ocean seems like such a big deal in Digimon Adventure 02. Governed by Dragomon and considered a separate dimension from the Real and Digital Worlds, the Dark Ocean is fueled by negative thoughts and plays a significant role in establishing Ken as Digimon Emperor.
The Dark Ocean is mainly limited to a single episode in Digimon Adventure 02, only resurfacing to be used as a convenient plot device to trap Daemon. It makes a reappearance in Digimon Adventure tri, once again being used to write an antagonist out of the picture. In the latter's case, Maki Himekawa was one of the original DigiDestined who become obsessed with reviving her fallen Digimon. After this fails, Maki is consumed by despair and ends up in the Dark Ocean. Her storyline ends with the waves taking her away. Again, not particularly satisfying.
The Crests... Just, The Crests
The Crests have always been a bit inconsistent. Represented by different characteristics and assigned to a compatible DigiDestined, Crests allow Digivolutions to be triggered when its defining traits are exhibited. Digimon Adventure ends with the big reveal that the Crests are only for show, as the power always came from inside the DigiDestined.
Or, that was the case before Digimon Adventure 02 nullified that plot point. As we could not have Tai's group running around with a bunch of Megas while Davis and company struggled to reach Champion form, the Crests were once again required to Digivolve. Digimon Adventure 02 was written while its predecessor was still wrapping things up, and you can tell.
Dark Gennai
Primarily known as the "Mysterious Man," Dark Gennai is a constant pain in the side of the DigiDestined throughout the majority of Digimon Adventure tri. Working for King Drasil to try and reboot the Digital World so humans can no longer interact with Digimon, Dark Gennai puts Meiko Mochizuki through hell and eventually causes the death of Daigo.
Dark Gennai's final appearance sees him successfully escaping while stating his refusal to give up on King Drasil's goal. Dark Gennai is mostly a secondary villain who does not get enough screentime, and his storyline's conclusion feels almost Team-Rocket-esque in execution.