Kamen Rider Kuuga

Yusuke Godai (五代 雄介, Godai Yūsuke)

A 24-year-old (later 25-year-old in episode 9) young, multi-talented adventurer who dons the Arcle belt, which turns him into the titular Kamen Rider Kuuga (仮面ライダークウガ, Kamen Raidā Kūga). He is a happy-go-lucky and honest person that fights to "protect everyone's smiles". Yusuke helps out at the Pole Pole while staying at the shop, and continuously attempts to master 2000 different skills and talents which he uses to help others. He lost his father, a war photographer, when he was a sixth-grade elementary school student, before losing his mother at the age of 18. He was born in Hokkaido on March 18, 1975.

Kaoru Ichijo (一条 薫, Ichijō Kaoru)

A 25-year-old (later 26-year-old in episode 15) assistant police inspector of the Security Division of the Nagano Prefectural PD. He is sent to the Unidentified Lifeform Joint Task Force Office, which is set up in the Metro PD to investigate and counter the Grongi. Like his father, who died on his tenth birthday, Ichijo is a model policeman who firmly believes in doing the right thing. Though he is very strict with himself, he will do everything he can, even bend police rules, to help Yusuke fight the Grongi. After the Grongi were defeated, Ichijo returns to Nagano. He was born in Nagoya on April 18, 1974.

Sakurako Sawatari (沢渡 桜子, Sawatari Sakurako)

A 23-year-old friend of Yusuke from a university and a graduate student at Jonan University who translates the ancient "Lintonese" transcripts that tell of Kuuga and the Grongi. At first, she was against helping because she was worried about Yusuke, but now she believes in him fully and works hard to help Yusuke understand his powers by deciphering the writings. She was born in Gunma Prefecture on October 30, 1976.

Minori Godai (五代 みのり, Godai Minori)

Yusuke's 22-year-old younger sister who works as a teacher at Wakaba School. Yusuke occasionally visited her there to entertain the kids. Like Sakurako, she was at first apprehensive about her brother transforming into Kuuga, but she believes in Yusuke and helps out however she can. She was born in Hokkaido on September 4, 1977.

Shuichi Tsubaki (椿 秀一, Tsubaki Shūichi)

A 26-year-old trusted friend of Ichijo from high school, he is the doctor who looks after Yusuke and treats him when he becomes injured, while also researching the effects of Yusuke's fusion with the Arcle. Though he's a light-hearted person, he was very serious and worried when talking about Yusuke's future transformations because of the constant dangers that surrounded the Kuuga legend. He also performs the autopsies of the Grongi victims in order to determine the causes of death.

Hikari Enokida (榎田 ひかり, Enokida Hikari)

A 34-year-old researcher of the National Research Institute of Police Science, she studies the biology of the Grongi in order to develop effective weapons against them. She also assists in the study of Kuuga and the Gouram. Because of the massive amount of work required of her to fight the Grongi, she was away from home quite often and her child felt lonely and neglected.

Tamasaburo Kazari (飾 玉三郎, Kazari Tamasaburō)

A 44-year-old former adventurer, he was friends with the father of Yusuke and Minori, who affectionately refer to him as Pops (おやっさん, Oyassan) like everyone else. He owns and runs the Pole Pole. He is a goofy, light-hearted character that keeps a scrapbook of all of Kuuga's exploits from the newspaper, though unaware of Yusuke being "ULF 04" and thinks that the name "Kuuga" is some nonsensical word made up by Yusuke. After learning the truth, however, he dons the Kuuga mark on his apron in the series epilogue. He was born on June 9, 1955.

Nana Asahina (朝比奈 奈々, Asahina Nana)

Tamasaburo's 17-year-old niece from Kyoto Prefecture, who helps out at the Pole Pole while aspiring to be an actress. However, since the death of her acting teacher at the hands of Grongi, Nana has been troubled until Yusuke finally helps her overcome her sadness.

Jean Michel Sorrel (ジャン・ミッシェル・ソレル, Jan Missheru Soreru)

A 27-year-old graduate student at Jonan University from France that shares the work office with Sakurako. He researched the broken fragments that later formed into Gouram. He has a crush on Enokida and hoped to help her reconnect with her child.

Sadao Matsukura (松倉 貞雄, Matsukura Sadao)

The 57-year-old head of the Security Bureau of the Metro PD and the head of the Unidentified Lifeform Joint Task Force Office.

Morimichi Sugita (杉田 守道, Sugita Morimichi)

A 37-year-old detective of the First Investigation Division of the Metro PD who is also a member of the Unidentified Lifeform Joint Task Force Office.

Tsuyoshi Sakurai (桜井 剛, Sakurai Tsuyoshi)

A 26-year-old detective of the First Investigation Division of the Metro PD who is also a member of the Unidentified Lifeform Joint Task Force Office.

Nozomi Sasayama (笹山 望見, Sasayama Nozomi)

A 21-year-old policewoman of the Unidentified Lifeform Joint Task Force Office who sends communication from headquarters.

Mika Natsume (夏目 実加, Natsume Mika)

The 14-year-old daughter of Professor Kokichi Natsume, and one of Daguva's victims, she was greatly depressed when her father's murder was being overlooked for the Grongi attacks, taking the findings her father had at their house. But after Yusuke reasons with her, Mika decides to aid in the Grongi matter as Jean's assistant. However, she is unable to follow and decides to take up playing the flute her father gave her. But while attending the 12th Arikawa Group Flute Competition, a hostage situation by a disgruntled government worker traumatizes Mika as Yusuke tells her not to run from her fear and continue. Three months later, Mika attended a special college.

Akiji Kanzaki (神崎 昭二, Kanzaki Akiji)

Yusuke's 52-year-old elementary school teacher, he served as an inspiration to Yusuke, and the two of them visit on certain occasions.

Junichi Chono (蝶野 潤一, Chōno Jun'ichi)

A 22-year-old young troubled man, he saw the Grongi as salvation until he was saved by Kuuga. He later researched trying to make a living until he was knocked out by Go Gamego Re while on his way to a contest.

The Grongi Tribe (グロンギ族, Gurongi-zoku) is a mysterious ancient civilization whose members can transform into monsters to kill people for their ruthless game, referred to in their language as the "Gegeru" (ゲゲル, Game). The two hundred members of the Grongi made their rival civilization the Linto (リント, Rinto), humanity's ancestors before they were defeated and sealed by the original Kuuga, Riku. However, the seal was undone in 2000 with the Grongi resuming their Gegeru on the human race that are the Linto's descendants to bring about the "Ultimate Darkness" (究極の闇, Kyūkyoku no Yami), when humanity will become as violent as the Grongi.

The Grongi are classified as Unidentified Lifeforms (also known as "ULF") (未確認生命体, Mikakunin Seimeitai), while those that have a human form are labeled "B" (B群, Bī-gun). Each of the Grongi possesses a stylized Gedoruudo (ゲドルード, Gedorūdo) with a Geburon (ゲブロン) stone. The naming pattern of the Grongi is "Group Species Creature type": the first part denoting their rank, the second part is the personal name, and the third part indicates the type of animal they resemble. Only 25 out of the 200 Grongi appeared in the course of the series.

In the series, the Grongi speak in their own native language (originally created by the producers as a cipher of Japanese language) which was left purposely unsubtitled during the original broadcast in order to prevent the audience from learning the series' mysteries and plot twists (as it was referred by them in the early episodes)). The Zu Group are the first to play in the Gegeru, then the Me, and finally the Go in the Gerizagibas Gegeru (ゲリザギバスゲゲル, Semifinal Game). The Gegeru is overseen by the two Ra Grongi, and the winner of the Gerizagibas Gegeru receives the right to challenge their leader, N Daguva Zeba, to a duel known as the Zagibas Gegeru (ザギバスゲゲル, Final Game) for the leadership of the Grongi.

The Ra Group (ラ集団, Ra Shūdan) are the judges of the Gegeru and are Daguva's right-hand men. The Nu Group (ヌ集団, Nu Shūdan) crafts the artifacts used by the other groups. The Zu Group (ズ集団, Zu Shūdan) contains lower-tier Grongi under Zu Zain Da, most of their kin slaughtered by Daguva as they failed to acquire the right to participate. Those who did qualify are brought into the Gegeru by writing their names on the portable Dodozo (ドドゾ, Board) blackboard and using the beads of their Guzepa (グゼパ) bracelets to mark the number of people they have killed. The Me Group (メ集団, Me Shūdan) are middle-tier Grongi led by Me Garima Ba, its members brought into the Gegeru by using the Bagundada abacus to predict the number of people they are to kill and the time period to accomplish that. The Go Group (ゴ集団, Go Shūdan) are high tier Grongi who can transmute their ornaments into weapons like Kuuga displays while in his Pegasus, Dragon, and Titan forms. Unlike the lesser tiers, the Go having Ra Dorudo Gu tally their kills for them while creating their personal rules of conducting their kills. The Go who completes the Gegeru, or the one who can defeat all the Go class Grongi, earns the right to fight Daguva for control of the entire Grongi Tribe. Their leader is Go Gadoru Ba, one of the three strongest Go Grongi who had modified themselves to alter their forms like Kuuga and Daguva. The lowest Be Group (ベ集団, Be Shūdan) were all murdered by Daguva without acquiring the right of the Gegeru.

N Daguva Zeba (ン･ダグバ･ゼバ, N Daguba Zeba)

The stag beetle-like lord of the Grongi and primary antagonist of the series, called by his kin as the "harbinger of ultimate darkness" (究極の闇をもたらす者, Kyūkyoku no Yami o Motarasu Mono). Sealed away by the previous Kuuga Riku, Daguva was resurrected in modern times in his Imperfect Form (不完全体, Fukanzentai), labeled as "Unidentified Lifeform 0" (未確認生命体第0号, Mikakunin Seimeitai Dai Zero-gō) by the police, slaughtering Riku's sleeping body and the archaeologists who broke the seal. Spending most of the series killing 152 of his own kind he deemed unworthy to participate in the Gegeru, Daguva resurfaces in his fully restored Perfect Form (完全体, Kanzentai). By the time he resurfaces after killing Goma, Daguva assumes the guise of a white-suited young man with an aura whom the police labeled as "Unidentified Life Form B13" (未確認生命体B群13号, Mikakunin Seimeitai Bī-gun Jū-san-gō). After Gadoru's death, Daguva begins his endgame with endless heavy rain and initiates a systematic genocide of all people in Japan. He is eventually killed by Yusuke after an epic fight that pushed the other to his limits, Daguva dying from his injuries while mocking Yusuke would become as violent as he is.

Ra Baruba De (ラ･バルバ･デ)

A rose-like Grongi who is only seen in her disguise as the woman with the rose tattoo (バラのタトゥの女, Bara no Tatu no Onna) wearing the Gegeru Ring (ゲゲルリング, Gegeru Ringu), labeled "Unidentifiedfife Form B1" (未確認生命体B群1号, Mikakunin Seimeitai Bī-gun Ichi-gō). She serves as the judge for both Zu and Me Groups, authorizing any member of the Grongi to enter the Gegeru. Following her many encounters with Kaoru Ichijo, including one where he injured her, Baruda realizes the humans can no longer be underestimated. Once Daguva begins his rampage, she is encountered by Ichijo and hints that humans will soon become like the Grongi before running off, with Ichijo being forced to shoot her with eight nerve-breaking bullets. Her body falls into the sea and is never found.

Ra Dorudo Gu (ラ･ドルド･グ)

A condor-like Grongi armed with a pair of tonfa, assuming the form of a man in black with white robes on him while labeled "Unidentified Lifeform 47" (未確認生命体第47号, Mikakunin Seimeitai Dai Yonjū-nana-gō) and "B9" (B群9号, Bī-gun Kyū-gō). He carries an abacus called the Bagundada (バグンダダ, Counter) which he uses to count the number of kills by the Go Group Grongi until Ichijo destroyed it with a marking bullet. This forces the purposeless Dorudo to fight for his life against Gadoru as Ichijo arrives to the scene, Dorudo ending up being killed by the Sugita and Sakurai using the completed nerve-breaking bullets.

Nu Zajio Re (ヌ・ザジオ・レ)

A salamander-like Grongi and the last of the Nu Group, labeled "Unidentified Lifeform B14" (未確認生命体B群14号, Mikakunin Seimeitai Bī-gun Jū-yon-gō). Posing as a middle-aged man, Zajio manages to remain in hiding with his existence unknown to the police while creating the items used by the Grongi. With Goma's aid, Zajio obtains discarded pieces of Daguva's buckle and refines them to create a means for a Grongi to have the same abilities as Daguva and Kuuga, so those in the Gegeru can defend themselves against Daguva. In the end, Zajio is eventually killed by Daguva just as he finished his final work. Like Baruba, Zajio's true form was never revealed.

Zu Goma Gu (ズ･ゴオマ･グ, Zu Gōma Gu)

A photophobic vampire bat-like Grongi labeled "Unidentified Lifeform 03" (未確認生命体第3号 Mikakunin, Seimeitai Dai San-gō) and "B2" (B群2号, Bī-gun Ni-gō), Goma initially murdered a preacher named Father Jose and disguised himself to use a church as a base of operations before Ichijo uncovered the truth and the Grongi is ultimately forced to retreated. Following Zu being removed from play, wearing a trenchcoat and fedora to protect himself, Goma becomes Baruba's underling. But Goma retrieved a discarded piece of Daguva's buckle and had it refined before using it evolve himself into his Strengthened Form (強化体, Kyōkatai) to have freedom of movement in daylight. But it also increased Goma's bloodlust as he turns on Baruba and intended to kill Daguva to gain his power, driven off by Gadoru as the final stages of his evolution take effect. Fully evolved into his armored Ultimate Form (究極体, Kyūkyokutai), Goma nearly kills Kuuga when Daguva finally arrives. Goma runs off to fight Daguva, only to be slaughtered by him with his corpse used to develop the nerve-breaking bullets. Goma's name in Japanese comes from the readings for "fiend" (強魔, Gōma).

Zu Zain Da (ズ･ザイン･ダ)

The hotheaded rhinoceros-like leader of the Zu Group, labeled "Unidentified Lifeform 22" (未確認生命体第22号, Mikakunin Seimeitai Dai Nijū-ni-gō) and "B3" (B群3号, Bī-gun San-gō), assuming the form of a hulking strongman with a temper. Soon after his group was removed from the Gegeru in favor of the Me Group, Zain starts acting on his own after the Grongi Tribe's first lair was raided, attacking trucks and impaling drivers with his horn. He overpowered Kuuga in both human and Grongi forms when Me Biran Gi intervened as Zain stole his turn. While Zain resumes his attack on large motor vehicles, Yusuke manages to perfect his Mighty Kick to finally kill the Grongi.

Me Garume Za (メ・ガルメ･レ)

A smart chameleon-like Grongi, labeled "Unidentified Lifeform 31" (未確認生命体第31号, Mikakunin Seimeitai Dai Sanjū-ichi-gō) and "B4" (B群4号, Bī-gun Yon-gō). Originally Zu Garume Re (ズ・ガルメ・レ), he is promoted between the Gegeru of Unidentified Life Forms 10 and 11, desiring to become a Go and played a part in murdering Nana's acting teacher. Posing as a man with wild blonde hair, Garume's turn came as he uses his cloaking abilities to hide at high areas, dragging his victims with his tongue to hang them while smashing their faces against a surface, announcing his next location to kill, going for the Komazawa Square and then at the Central Tower, where the police stand by. Learning of a five-minute window, the police attempt to use flash grenades to disrupt Garume's chromatic cellular makeup while learning the reason for the Grongi attacks. Though the visible Garume outruns the police, he runs into Kuuga as they battle. But once Garume turns invisible to escape, he is killed by Kuuga's Gouram-aided Blast Pegasus. The encounter with Garume, who tends to speak Japanese, together with Ichijo's experience with Baruba, leads to the police to realize that the Grongi are capable of speaking their language as well.

Me Garima Ba (メ･ガリマ・バ)

The mantis-like leader of the Me Group, labeled "Unidentified Lifeform 36" (未確認生命体第36号, Mikakunin Seimeitai Dai Sanjū-roku-gō) and "B6" (B群6号, Bī-gun Roku-gō). Garima has a tattoo on her right pointer and thumbnails and a green streak in her hair while in her human form. While Garume begins his Gegeru, Garima receives a double-bladed scythe/lance as the Go arrive and she was on a train at the Ochanomizu Station, killing those in the 4th cabin as the others left. Deciding to continue playing as one of the Go, she tracks down the remaining the 288 who left the train prior and strikes them down with her weapon, her victims unaware of their death until they look back to face her. When Kuuga attempts to fight her in Titan Form on the Gouram, Garima manages to endure the TryGouram Attack and escape in the confusion, wounded but able to continue the Gegeru with her scythe-katana. She was about to kill Sakurako when Yusuke arrives at her aid, assuming Rising Titan and running through Garima.

Go Bada Ba (ゴ･バダー･バ, Go Badā Ba)

A grasshopper-like Grongi, labeled "Unidentified Lifeform 41" (未確認生命体第41号, Mikakunin Seimeitai Dai Yonjū-ichi-gō) and "B8" (B群8号, Bī-gun Hachi-gō). The first of the Go to appear when he intervenes in Kuuga's fight with Goma before leaving the scene and then formally introducing himself when Go Bemiu Gi starts to play. Assuming the form of a young man wearing a red scarf (which pays homage to Kamen Rider 1) and carrying a coin, Bada rides a motorcycle named the Bagibuson (バギブソン, Cyclone) as his weapon that can reach speeds of 400 km per hour. When his turn came, he begins to kill 99 motorcyclists. When the Try Chaser 2000 is damaged, Kuuga is left at a disadvantage as Bada leaves with a promise to save him in his Gerizagibas Gegeru. By the time Bada reached 98, he decides to finish off Kuuga. However, after being barraged with bullets, Bada is driven into a secluded location where Kuuga meets him on the BeatChaser 2000, outrunning him and assuming Rising Mighty before he fatally knocked Badaa off his motorcycle.

Go Gadoru Ba (ゴ･ガドル･バ)

The fierce rhinoceros beetle-like leader of the Go Group and one of the three strongest Go Grongi, labeled "Unidentified Lifeform 46" (未確認生命体第46号, Mikakunin Seimeitai Dai Yonjū-roku-gō) and "B11" (B群11号, Bī-gun Jū-ichi-gō). Armed with various weapons similar to Kuuga, he assumes the form of a man in militant garb. As the Go's leader, he intervenes in the fight between Go Zazaru Ba and Goma and later comes to Baruba's aid against a power-mad Goma when Kuuga arrives to witness him putting the bat-like Grongi back in his place. With Daguva going to Tokyo soon, he and the other two remaining Go Grongi undergo the same process as Goma to ready themselves. After his two allies were killed, Gadoru is the last of the Grongi to play. After undergoing training to ready himself, Gadoru heads to the police department to find worthy opponents to fight as part of his Gerizagibas Gegeru. When confronted by Kuuga in his default Grapple Form (格闘体, Kakutōtai), Gadoru reveals his new ability to use the different powers of Kuuga, Quick Form (俊敏体, Shunbintai), Shooting Form (射撃体, Shagekitai), and Herculean Form (剛力体, Gōrikitai), before defeating Kuuga at full power in Shocker Form (電撃体, Dengekitai). But due to Ichijo, Gadoru's Gerizagibas Gegeru had to be reset as the Grongi attempts to kill Dorudo for failing his part. After Dorudo retreats, angry Gadoru attempts to kill Ichijo upon being wounded by the officer's nerve-breaking bullets as Yusuke arrives to battle the Grongi as Kuuga. Once taking their fight to the woods, Kuuga assumes Amazing Mighty and destroys Shocker Form Gadoru.