GARO focuses on the life of Kouga Saejima, who assumed the title of Makai Knight to protect humanity against dark demonic manifestations called "Horrors." In his quest to purge them, he encounters a young girl named Kaoru whom he saved from a Horror, but was stained with its demonic blood. As a rule, those that been stained by the blood of a Horror shall be cut down, or else they will die painfully in approximately 100 days. Kouga had mercy upon her and tries to find a way to purify her before her remaining time expires. Thus, the series focuses on Kouga's developing relationship with Kaoru and his stand in protecting humanity after the wishes of his father, who was his predecessor with the title of GARO.
(taken from wiki)

Picture	Cast	As	Description
	Hiroki Konishi	Kouga Saejima / Golden Knight GARO / Fanged Wolf / Kiba Okami	He is the Golden Makai Knight of the East. He is a young man who apparently thinks nothing else than destroying Horrors. His father was the one that started his training at an early age. He is not a sociable person and always keeps his feelings to himself, but possesses a noble and kind heart behind his emotionless façade. He spared Kaoru's life because she reminded him of his mother. As GARO the Golden Knight, his armor helps protect him from damaging blows, but his armor isn't unbreakable. If a Horror is strong enough, they can damage and injure Kouga. The Sword of GARO is a powerful weapon that can cut down almost anything and only a rare few Horrors are strong enough to resist its force.
	Mika Hijii	Kaoru Mitsuki	She is a 22 years old aspiring artist who's always having trouble making money. Kouga spared her life after she was splashed with Angry's blood. Because of the Horror blood that stained her, she attracts Horrors constantly; she doesn't know she's being pursued half the time because Kouga does his best to quietly deal with the Horrors that try to approach to her. Later it is revealed that Kaoru's father and she have been involved with Horrors and GARO since her childhood.
	Ray Fujita	Rei Suzumura / Silver Fanged Knight ZERO / Ze Wolf / Ze Okami	He is the Silver Makai Knight of the West. He was an orphan and the knight that wielded the Silver Fang armor at that time took pity on him and raised Rei as his son, training him to inherit the title and start his own lineage, continuing the tradition of guardianship. One fateful night, his lover Shizuka and his father were killed by a warrior who suspiciously resembled GARO. So he renamed himself ZERO and has had a vengeful spirit to get back the Makai Knight that took his loved ones away ever since. During ZERO's quest for revenge he violated a host of protocols expected of a Makai Knight. He left his western territory post and barged into Kouga's eastern post.
	Yukijirou Hotaru	Gonza	He is the butler of the Saejima household and the only family Kouga had after his parents died. Gonza does all butler related activities and also advises Kouga on certain matters when Kouga doesn't understand. He helped raise and assist Kouga with his training since childhood. Though he as been exposed to the Makai world for over twenty years (between Taiga and Kouga), Gonza is a regular person without any form of Makai training other than being a butler.
	Mina Fukui	Asami	She's Kaoru's best friend. She always helped Kaoru's financial problems by giving her financial tips, loans, and job references. When Kaoru lost her apartment Asami reluctantly allowed Kaoru to move in for a few days. Kaoru made a dish for Asami as a way to appease her, but made her sick instead.
	Hironobu Kageyama (Voice)	Zaruba	Zaruba is the Madou Ring for Kouga's duties as a Makai Knight. Zaruba originally belonged to Taiga Saejima. After Taiga was killed, Kouga has since worn his father's ring. Zaruba himself was created by the Makai Priest Amon who creates the anti-Horror equipment to aid and support a Makai Knight.
	Ai Orikasa (Voice)	Silva	Silva is the Madou Necklace of ZERO. She belonged to the former Silver Fang (Rei's father) and serves the current one. She takes the form of a Madou necklace of a woman wearing a mask. It was Silva that identified the killer of ZERO's family was related to another Makai Knight.
	Yasue Sato	Jabi the Makai Priest	Jabi was student under Makai Priest Amon and was a former childhood playmate with Kouga. She and Kouga trained together, but when their separate ways during their teenage years. By the time the two crossed paths, Jabi was framed with the murder of her mentor and had stolen the purified Horror blades due to be forced repatriated. Though Kouga believed she wasn't responsible for the murder, Jabi was unable to trust him because Amon's murderer was a Makai Knight. But eventually, Jabi began to trust Kouga again. Jabi is a sensually aggressive woman and wants to be a good woman rather than being a talented Makai Priest. She carries two Makai brushes to summon electrical attacks and has two red Makai flags used to ward off certain magical attacks.
	Masaki Kyomoto	Ryuuzaki Karune / Barago / Dark Fang KIBA	Barago was once a talented Makai disciple of Taiga Saejima. Barago lost his loved ones to the Horrors and relied heavily on the powers of the Makai for revenge. But refused the right to become the next GARO, Barago's desperation for power grew and KIBA heard his need. Barago was lured into a forgotten lair filled with forbidden techniques. Barago desired power so much that he agreed to give up his body and soul to KIBA for vengeance. Barago used a potion he has stolen from Rei's family to change his face, disguising himself as Ryuuzaki Karune, who is also Kaoru's personal psychiatrist and counselor.
	Mark Musashi	Kodama	Kodama is the "butler" of the Watchdogs, Eurasian in appearance, and his relationship with them is that he is their son. Kodama's position has him serve the Watchdogs, carrying out their orders and protecting them from harm. He's highly skilled in martial arts and doesn't fear taking on a Makai Priest or Makai Knight. Though apparently unable to talk, Kodama can use his voice to summon magical destructive blue orbs, and throw them at his enemies. The longer and louder he can shout, the bigger and stronger the magical orbs will be.