Known as the "Golden Knight", Kouga is a renowned Makai Knight who inherited the title from his father, Taiga Saejima. His weapon of choice is a longsword. While he is coldly dedicated to his mission at the start of the series, even heartlessly using Kaoru as bait for Horrors, he slowly begins to care for her without ever losing his stoic personality.
BFS: His powerful sword is already big to begin with. Then when he rides his horse, Gouten he can transform it into a insanely huge version of it, ''Zankantou-style'' to take down Horrors the size of houses.
Screw the Rules, I Have Money!: Kouga is ridiculously wealthy and won't hesitate to use his money in pursuit of his mission. When confronting a Horror that has possessed an actor taking the lead role in a play, he ensures a one-on-one showdown by buying all the tickets.
Single-Target Sexuality: Even though he has two incredibly sexy Makai Priests who have shown some sort of interest in him and in a series where there is fanservice abound, Kaoru is the only person Kouga has shown any romantic attraction to. In the short time they were together, he fell for her, and stayed in love with only her even during the times when they were seperated.
Trauma Conga Line: Where do we start? As a child, Kouga not only witnesses the traumatic death of his father but also the deaths of his childhood Makai-training camp friends whom he witnessed GET EATEN right before his eyes! As an adult, he is isolated, emotionally repressed, socially awkward, and ruthlessly devoted to a frankly horrific job that will probably end up getting him killed at a young age. Despite all this, he meets the love of his life under horrible circumstances in which she is cursed to die in a hundred days. He literally goes through hell to retrieve her cure, they get a breather, and then they find out that she's actually a gate for the ultimate Horror to pass through. Her trusted mentor is actually the Big Bad who killed his father and who invokes an even Bigger Bad to possess her body. While this is happening, Kouga is getting his ass kicked by Barago, Kodama (during which he nearly became a soulless monster), GULM, Messiah!Kaoru, Messiah, and then Barago's armour KIBA. Oh, and then his magic talking ring dies. And then, the girl he did all of it for leaves for Italy. Yeah, she comes back but still.
Come in the second season, he is the one cursed to die this time around, and just as he thinks that's about to be resolved, he gets almost permanently absorbed by the corpse of the demon Ganon to help create Idea, a monstrous robotic weapon designed by a man who wishes him and every other Makai Knight dead simply for being "not good enough" at fighting the Horrors.
Tsundere: Kouga is a male version of this towards Kaoru. Even though he loves her, he still hasn't quite figured out the mechanics of expressing that affection in way that doesn't make him look like a jerk or incredibly awkward.
Rei Suzumura (ZERO)
Known as the "Silver Fang", Rei is a Makai Knight who shirked his responsibilities to pursue a personal vendetta against Kouga, who he believes murdered his lover. He wields two swords that can combine into a single weapon when in his armour. Though he acts friendly and familiar, his true personality is cold and focused.
Dual Wielding: Wields two powerful short swords skillfully in combat.
Enigmatic Minion: At first, but he mellows out by the end of the series once the misunderstandings are cleared up.
Heel-Face Turn: While not evil persay, he starts as an enemy due to a major misunderstanding and the manipulation of the Eastern Watchdogs. After the truth comes to light, he becomes a staunch ally.
Ineffectual Loner: May have something to do with his Dark and Troubled Past, he mostly try his best to shun contact from anyone after battle. Even if they are friends. Still, he will never hesitate to lend a helping hand when the time comes.
When she is introduced, she is a struggling young artist whose life becomes entangled with Kouga's after she is caught in the middle of a fight between Kouga and a Horror. In the ensuing battle, she is splashed with the monster's blood and afterwards cursed to die in a hundred days. Kouga initially decides to use her as Horror bait but as they grow closer, he ends up falling for her and is determined to protect her at all costs.
Morality Pet: For both Kouga and Rei, mostly in the first series.
The Pollyanna: Kaoru is almost aggressively determined to be this no matter what hardship she goes through since she realizes that she has no control when it comes to Makai matters and the best she can do is put up a facade of unwavering optimism. Even after she finds out that Kouga is dying she refuses to allow anyone see her despair and only breaks down once she is alone.
Trauma Conga Line: Starts off the series as a struggling artist and then she gets splashed by demon blood and is condemned to die in a hundred days, is attacked on what almost appears to be a daily basis by demons and occasionally Rei, finds out the guy she was falling in love with not only knew that she had very little time to live and was keeping it a secret but actually kept her alive for the sole purpose of using her as monster bait, betrayed by Rei in order to get to Kouga, and then narrowly escaped her death sentence at the last second. But just when things were starting to look up, she finds out her mentor had actually manipulated her into becoming the Big Bad, she gets kidnapped once again, becomes possessed by the Mother of all Horrors and is forced to fight her friends. Of course, everything worked out for her in the end. Of the first series that is. Flash forward to the second series and this time around her boyfriend is the one that's dying. Girl cannot get a break.
Unwitting Pawn: She wasn't simply being used by Barago, who manipulated her ever since she was a child to become Messiah's host but also by Kouga, who initially only spared her life to use her as Horror bait. Although the latter later came to regret his actions. The former as well but for very different reasons.
Characters Introduced in GARO (TV)
A psychologist who acts as Kaoru's confident and emotional support. He is secretly BARAGO, having taken the guise of Karune Ryuzaki to keep a close watch on his Apocalypse Maiden.
Badass: She's no Makai Knight, but she can kick serious amounts of ass with her skills. She even manages to duel the Big Bad of Makai Senki to a standstill, although she is visibly exhausted afterwards.
The three young girls who act as Kouga's superiors in the first series of GARO. Named Keira, Beru and Rose, they are ancient Makai Priestesses who almost seem to share a single mind. As Watchdogs, their main role is to give execution orders to Kouga when a powerful Horror is detected, and perform the Makai Purification ritual on Kouga's sword. They are secretly working to revive Messiah.
Battle Butler- he can go toe to toe with Kouga and Rei in terms of combat prowess.
The main antagonist of the first series of GARO. BARAGO is known as the Black Fang, a fallen Makai Knight who was granted the forbidden power of the Demon Knight KIBA. This allowed him to surpass the 99.9 second time limit on his armour, and to consume Horrors to increase his own powers. His goal is to achieve ultimate power by absorbing one thousand Horrors, with the final one being the Ultimate Horror, Messiah.
Badass: Sure, he is evil but that doesn't stop him from being one.
Armor-Piercing Question: Gets a deep one from Kouga about his belief that he needs to discard his emotions in order to become strong.
Kouga: Makai Knights fight for those who must be protected. Tsubasa... Who is the one you must protect?
Kouga: ...must you protect? It's the person you feel more for than anyone else. Remembering that face... Someone you'd give your life in battle to protect. Rin loves you. That's why she wanted to protect you. That's why she faced Legules. Isn't Rin the one you should be protecting?!
A hot-headed Makai Priest. She resents the fact that she was denied the opportunity to become a Makai Knight because of her gender, and trained herself to actively hunt Horrors on her own. However, her lack of discipline and furious determination often results in civilian casualties.
A former Makai Guide who was betrayed and fatally wounded by two Makai Knights while looking for the corpse of Ganon. She is rescued by Barago, who was also looking for Ganon's corpse, and vows to serve him.
Gratuitous English - her explanation of her backstory to Kaoru in KIBA is done in English with Japanese subtitles a la the intro to the series proper.
A genius Makai Priest who becomes the support for Kouga in Makai Senki. He is responsible for a number of inventions, such as the mechanical Gouryuu that can allow Makai Priests to seal weaker Horrors without the need for a Makai Knight. Despite his achievements, he conducts himself with great humility and poise. He is secretly a Makai Knight as well, whose title is RŌDO, the Flash Knight.
Crouching Moron, Hidden Badass: He doesn't act like an idiot but his shyness makes some people around him think of him less. Especially some of his Jerkass Makai Priest superiors. That's why they tend to forget that he's very dangerous in combat.
Not to mention that he's secretly a skilled swordsman & a powerful Makai Knight.
Hidden Depths: Revealed to be a skilled swordsman despite being a Makai Priest. He can also transform into a Makai Knight. His title is RŌDO, the Flash Knight
Drill Sergeant Nasty: ''Famed'' in the Makai community as a relentless & demanding instructor of troubled Makai Knights in training. But he does genuinely cares about his charges/students. He was also Kouga's instructor when he was young.
The main antagonist of Makai Senki. The Man In The Red Mask is a rogue Makai Priest who is attempting to destroy the Makai Knights, believing that they are unneeded and that Makai Priests should be solely responsible for dealing with Horrors. To this end, he brands as many Makai Knights as possible with the Brand of Destruction, develops anti-Horror technology such as humanoid Gouryuu, and attempts to sway Makai Priests to his side. In addition to his incredible magical prowess and intellect, he is also a skilled swordsman and fighter. His true identity is Sigma Fudou, Leo's identical twin brother.
Human Resources: He has no issue with killing and experimenting on humans to achieve his goals. His familiar Gigi was originally a human woman whom he murdered, and he plans to fuel Edea with the lives of "sinful" humans.
Man Behind the Man: Subverted. Unlike Messiah, Ganon had no grand scheme to resurrect herself and did nothing to manipulate Sigma; she was dead after all. It just so happened that Sigma's malice was enough to trigger a resurrection, and once awakened Ganon did what any Horror would do.