Final Fantasy III has a manga.
On its own, this doesn't sound too surprising. Final Fantasy has had a vertiable horde of adaptations after all, such as novels or mangas. Even Final Fantasy I got a manga (a rather interesting one) and Final Fantasy II has a novelization that is the source of The Emperor's true name (which itself gets nods in the games, if never used directly). So, what makes III different?
III... is weird.
The manga features most of the guests from the game: The lone guest to be missing is Aria, and even then, she has a spiritual successor of sorts. But we'll get to that.
The manga was the first media to give the main characters set identities. While very distinct from the remake's cast, there are some similarities that blur the possibility of homage vs coincidence.
As the manga was written by the scenario writer, Keji Terada, these characters are technically the closest to "canon" identities of the Famicom party. However, the manga has significant differences to the game and unlike the FF2 novelization (which contributed the "Mateus" name), the III manga has never officially been acknowledged by SE to my knowledge.
Muuchi is one of the three youths of Ur, alongside his adopted brothers Doug and J Bowie. All three of them are mischevious, stealing from merchants and overall being brats. Over the course of the manga, however, he grows into a capable hero in his own right. Muuchi favors swords in battle, using dual blades in the early chapters and a single sword in later chapters. That said, he certainly isn't afraid to use his fists if need be.
His design seems to take cues from the Warrior job. All of the main characters go through outfit changes throughout the manga, but Muuchi favors armors. Muuchi's hair color differs between black, brown and blue-ish.
Doug is the second of the three youths of Ur. He's a little guy who usually (but not always) keeps an optimistic air. Unlike the other heroes, he doesn't use magic; Instead prefering knives and a sort of bendable flail.
Doug's design is vaguely remeniscent of the ranger job, albeit with a headband rather than a hat. Much like Muuchi, his outfit changes as the story goes on. His color scheme also varies the most heavily of the group: He's usually blond with a yellow and green clothes scheme, but one cover protrays him as silver-haired with a silver and yellow color scheme.
The third of the three youths of Ur. Of the four, he's the oldest and has a more stoic and calm demeanor. Despite this, he is actually just as prone to causing mischief as his brothers at the start of the manga.
During the first half of the manga, he uses twin knives (and some sort of wire aparatus?) as his main weapon. Later, as he becomes more attuned to Black Magic, he uses a staff to conduct it.
The last of the four Warriors of the Wind and the only one not native to Ur, Melfi is from the next town over, whose parents were killed in the Great Earthquake. She meets the boys at the Wind Shrine, helping them defeat the Land Turtle and while she is initially unimpressed by their antics, she grows to respect all of them, especially Muuchi.
She also gets some metaphysical spirit realm thing that usually entails her as a naked spirit or ghost or something?
Melfi primarily uses a bow and arrows as her weapon. When she gains the ability to use white magic, she uses that both for healing and offense.
Cid: Cid appears in the first volume of the manga, after the heroes fight the monsters in the ghost town. He tells the heroes of what went down at Castle Sasune and accompanies them there. Later, Cid uses his airship to help the heroes travel around the continent in the first half of the story. In this version, the pack on Cid's back functions as a helicopter pack, allowing him (or anyone who uses it) to fly.
Sara: The Princess of Sasune, she appears in the second half of the first volume. Compared to the games, Sara's not quite as capable here; She's initially held captive in the castle by the (giant and far more manacing) Djinn and seemingly killed when the tower she's in blows up. While she escapes thanks to Cid, she doesn't get to contribute directly to the battle. Her necklace does play a key role in sealing him, however.
Desch: One of the more extensively altered characters, Desch appears towards the end of the first volume, atop the back of a massive bird and looking far more sinister. Desch functionally serves as the main antagonist for a significant chunk of the manga: abducting people and brainwashing them into following him: One of those people in question being Muuchi. However, Desch turns out to be under the influence of an evil tree: Once Melfi destroys the evil within it, everyone brainwashed by the tree is released from its influence, including Muuchi and Desch.
Desch tells the party of Hein and joins them in infiltrating his castle and fighting the mage. After Hein is defeated, Desch sacrifices himself to the Elder Tree (?), in the process opening the way for the Warriors of the Wind to reach the surface world.
While Desch's artwork has him carrying a sword, with the remake realigning him as a Red Mage-like character associated with Lightning, The manga portrays him as a monk-like character, having great strength and fighting with his fists. He also shows an affinity towards birds; moreso during his evil phase, but during the fight with Hein, Desch calls one in to attack him.
Hein: Hein appears as the major villain of the second half of chapter 2 and the first half of chapter 3. In this adaptation, in lieu of the barrier shift, he has power over Shiva and Ifrit due to a magic ring. He mostly uses them to fight, with Shiva freezing the party and Ifrit fighting Muuchi.
Eventually, Hein fuses with Ifrit and Shiva into a monster. He manages to get the upper hand over Muuchi both physically (stabbing him; Muuchi thinks about his friends, which emboldens him) and mentally (he creates illusions of a clone Muuchi's head melting and a grotesque worm creature emerging from Muuchi's gut to eat him. However, thanks to Ifrit & Shiva, Muuchi is able to get a grip and defeats Hein.
Alus: The Prince of Solrados, Alus appears mid-way into the third volume, descending from the heavens with a group of men to save the Warriors of Light from monsters. He guides them to the crystals, explaining the downfall of his kingdom in the meantime and even saving Melfi from falling off a cliff. He gets lost in the chaos as an earthquake happens and the crystals are unearthed. Eventually, Unei returns, but Alus passes/dies (?) and Unei allows him to pass on.
In a manga full of weird changes, Alus' are probably the weirdest of them all. Alus' role in the manga matches much more closely with that of Aria in the games: Being the first person the party encounters on the surface, aiding the party in resurrecting the crystals and dying at the end of it.
Alus' age also appears to have been bumped up: In the games, Alus is stated to be 10. In the manga, however, he is as tall as the mid-late teenage party.
Doga & Unei: Much as in the game, Doga and Unei make their entrance late into the story. Doga spends most of his panel time confronting Xande while Unei is introduced a bit later. Unei primarily explains aspects of the plot, including putting the Warriors into a dream and showing them the duo's previous meeting with Noah. When the two unite, they leave the world in the hands of the Warriors of the Wind before passing on. Despite this, they still have a presence: As Xande is able to create clones to fight alongside him.
Xande: Xande is very different in this adaptation. He initially appears as a giant monster, with the reveal that this is a shell of some kind: His true self looks more akin to the unused Guardian summon, albeit still giant. Without a translation, it's hard to tell what Xande's deal is in the manga. Even so, he acts as the final boss of the manga, even having three forms (his armored form, his standard form and one last form that is the result of him surviving the Warriors of the Wind's final attack). He defeated when the four crystals impale him, resulting in the Floating Continent returning to the surface.