Icon-kyuranger.pngThis article is about a/an ranger in Uchu Sentai Kyuranger.

"Big Star! Koguma Skyblue"
―Koguma Skyblue's role call[src]

"Big Surprising Star! Ooguma Skyblue!"
―Ooguma Skyblue's roll call[src]

Kotaro Sakuma (佐久間 小太郎 Sakuma Kotarō) is a young boy who defied Jark Matter's occupation of Earth with his younger brother, Jiro Sakuma. Inspired by Stinger, Kotaro decide to join the Rebellion. He later gains his own personal Kyutama from Shou Ronpo's predecessor, Big Bear to become Koguma Skyblue (コグマスカイブルー Koguma Sukaiburū, lit. Little Bear Skyblue), the eleventh member of the Kyurangers.[1] He can turn into a giant version of himself, which is known as Ooguma Skyblue (オオグマスカイブルー Ooguma Sukaiburū, lit. Great Bear Skyblue).[2]

Aged 13, Kotaro was born on May 5th.[3]


Meeting the Kyurangers

While the adults refused to defy Jark Matter to make it easier for everyone, Kotaro and his brother refused to accept the oppression, leading to them being caught up in the fight between the Kyurangers and Jark Matter which resulted in the boys being caught by Stinger who, though ordered by Eriedrone to kill them, decided instead to keep them hostage so as to force the eight Kyurangers to surrender their Kyutamas. The brothers' bond reminded Stinger, secretly a Rebellion spy operating within Jark Matter, of that he once had with his own older brother and so he told them to watch out for each other. Ultimately, while Eriedrone intended to kill the brothers regardless, Stinger dropped his facade at the last minute, saving the boys before joining with the Kyurangers to take down Eriedrone, raising the hopes of the previously disillusioned adults. Tvicon.png TV STORY-Space.5: 9 Ultimate Saviors

Pursuing the Kyurangers

Some time after the Kyurangers victory, Kotaro follows the Kyurangers actions and locations, even going as far as getting into areas which were under Jark Matter's control. As Garu, Raptor and Stinger headed the last of the five Moraimarz they've taken down, he got caught by the Indaver but was saved by Stinger. He then reveals his intentions to join the Kyurangers to Stinger. Stinger brought Kotaro to the Orion, much to Shou Ronpo's surprise of bringing a kid in. As the Kyurangers were in a dire situation, Shou decided to get into action, telling Kotaro to stay and keep watch of the Orion. He even don't know what was going on when Lucky asks for Pega-san to be sent to them. Tvicon.png TV STORY-Space.8: Secret of Commander Shou Ronbou

After the Kyurangers made a hasty retreat, save for Spada, Kotaro still begs Shou to let him join the Kyurangers. He was left behind again when Shou went out alone in the rescue mission and the other Kyurangers finding the commander. After a successful mission and Shou suggesting a new name for the team due to having a 10th member, though rejected by the other Kyurangers, Kotaro still insist that he should be the 11th Kyuranger. This went to the point the Kyurangers were annoyed by his persistent attitude. Tvicon.png TV STORY-Space.9: Burn! Dragon Master

Joining the Kyurangers

Kotaro stays behind in the Orion and tries various Kyutamas to see which one was compatible with him, though Champ mentions that in order to become a Kyuranger, the Kyutama has to choose the user. At that time, the Ooguma Kyutama glows. When Lucky brought him back to Earth, Kotaro reveals that he took the Transformation Controller Seiza Blaster with him without the Rebellion knowing, much to Lucky's shock (similar to how Lucky took the blaster and going off with it in the very first episode). Lucky chases Kotaro to get the blaster back but were attacked by Daikaan Mozuma. The Ooguma Kyutama in Kotaro's bag flew to Lucky's blaster, resulting in Big Bear's spirit attacking Mozuma and possessing Kotaro. During their search for Mozuma, Kotaro reveals to Lucky and Big Bear that he decided to become a Kyuranger to be the shining star of hope that will save Earth. He also made this promise to his younger brother Jiro. They found Mozuma and Kotaro attacking them even without an ability to transform. Seeing Kotaro's resolve, Big Bear entrusts the Ooguma Kyutama to Kotaro and the Koguma Kyutama was created. He transforms to Koguma Skyblue, using the scarf to fight and prevents Mozuma from getting away before finishing with an All-Star Crash just in time for the Orion to evade the Sun. After returning to the Orion, Kotaro dons a cyan team jacket as the 11th member of the Rebellion. Tvicon.png TV STORY-Space.10: A Small Giant, Big Star!

When learning about the legendary ship Argo and all 3 kyutamas needed for it were on Earth, Kotaro was elated to be part of the operation, though he got disappointed that his kyutama did not come out of the Kyulette. He manages to sneak into the Shishi Voyager, much to the group's surprise. Upon encountering Jark Matter troops, the group fights them off, with Kotaro's childish fighting skills got into Stinger's nerves. When the team were trapped underground, Kotaro learns from Stinger about his reasons to fight and Scorpio. In the battle against the enlarged Deathworm, Kotaro was unsure if he was able to summon a Voyager, though with the encouragement of Stinger, he summons and operates the Kuma Voyager. He uses the Koguma Voyager to save Lucky in time. Tvicon.png TV STORY-Space.11: Three Kyutama to Save The Universe

Departing the Kyurangers

During the operation to free one of the districts from Jark Matter's control, which involved citizens turning into zombies due to Scorpio's venom, Kotaro joins the main team to cure the citizens. He even questions Stinger into thought of dealing with Scorpio and reasons of mentioning him into detail. After dealing the situation, the Kyurangers holds a party for Kotaro before his departure to the Rebellion main headquarters to train. Tvicon.png TV STORY-Space.13: Stinger's Challenge To His Brother!

Kotaro contacted Shou Ronpo as Rebellion HQ transported the Hikari Kyutama to the Orion to help the Kyurangers overcome Shaidos. Reporting that he was making good progress, Kotaro informed the team that Champ was still awaiting a series of assessments as his body was being repaired while Stinger continued to feel guilty for his injuries; Kotaro was entrusted by Shou to watch over them. Tvicon.png TV STORY-Space.17: Lighting the Dome of Darkness!

Kotaro Sakuma Card.png

Seeking the Kyutama of the Tokei System, the Kyurangers came to the planet Toki and turned the 12 keys needed to unlock it within 30 minutes. Approaching key XI, Kotaro was met by his late mother, Akemi Sakuma. He was conflicted when he found that turning the key would make her disappear, and she was concerned for her son's well-being as a warrior fighting Jark Matter. However, upon seeing his teammates' plight against Tecchu, Kotaro ultimately turned the key, telling his mother that he would save the universe. Tvicon.png TV STORY-Space.25: Planet Toki, the Boy's Determination!

Saving Naga

Kotaro was part of the team that decided to remain in the present day to save Naga while the other Kyurangers traveled to the past to discover Don Armage's secret. He and others, however, would have little luck until all Kyurangers except Champ and Shou were reunited in the present.

Returning to Earth

After some time crossing the galaxy, Kotaro would eventually return to Earth when the Kyurangers believed Don Armage was prepared to launch his final assault. He briefly reunited with his brother Jirou, who as then kidnapped by Doctor Anton. In retaliation after saving Jirou, Kotaro would help Champ and Stinger deliver the final blow to destroy Anton's core memory unit once and for all.

On the eve of the final battle against the Don Armage created from Ohtori Tsurugi, Kotaro wondered if he was any different from when he first joined the Kyurangers. Stinger replied that he was far stronger and had the potential to surpass Tsurugi over time.

Kotaro spent most of the final battle fighting alongside Stinger and Champ against an endless supply of Jark Matter soldiers, spearheaded by Champ 0s.


Two years later, Kotaro remained an active member of the Kyurangers, reporting directly to Stinger and patrolling a now peaceful universe.

Kotaro is forced to say goodbye again.


Kotaro has a high sense of bravery, not being afraid of defying Jark Matter. He is also protective of his younger brother and the people dear to him. After seeing the Kyurangers being able to bring hope to others, especially sharing a common brotherhood bond Stinger had whom Kotaro inspired, Kotaro went all the way to follow them, even intending to join the Kyurangers. His wish became true after gaining the trust of Big Bear and creation of the Koguma Kyutama to become Koguma Skyblue.

He calls Hammy 'Old Lady', much to her annoyance. Despite being the youngest member of the team, he has a mature personality, able to make correct decisions and helping the older members to reconsider their thoughts and reasons. He also has a strong determination to save Earth as the shining star of hope. However, due to his inexperience in battle, childish methods and tendency to butt into things without a strategy, he was sometimes a hindrance to the team. Despite that, Kotaro improves himself in fighting against the evil space empire.

Video game appearances

Super Sentai Legend Wars

Koguma SkyBlue Card

Render Of Koguma SkyBlueSuper Sentai Legend Wars

Koguma Skyblue appears with his team among all Sentai in the mobile game Super Sentai Legend Wars.

Powers and Abilities

Koguma Skyblue

Koguma Skyblue's insert theme is BLUE SKY BOY.

Koguma Skyblue

"Koguma Kyutama! Seiza Change!"
―Transformation announcement via Seiza Blaster[src]




  • Polaris Crush (ポラリスクラッシュ Porarisu Kurasshu): Koguma Skyblue performs a powerful blast attack with the Seiza Blaster.
  • All-Star Crash (オールスタークラッシュ Ōru Sutā Kurasshu): Koguma Skyblue performs a powerful blast attack with the Seiza Blaster alongside his fellow Kyurangers.
    • Kyuren All-Star Crash (キュウレンオールスタークラッシュ Kyūren Ōru Sutā Kurasshu, Nine Union All-Star Crash): An upgraded version of this finisher with the first 11 Kyurangers.
    • Ultimate All-Star Crash (アルティメットオールスタークラッシュ Arutimetto Ōru Sutā Kurasshu): An upgraded version of this finisher with the all 12 Kyurangers.
  • Polaris Impact (ポラリスインパクト Porarisu Inpakuto): Koguma Skyblue performs a powerful slash attack with his own Kyu Spear.
  • All-Star Impact (オールスタースインパクト Ōru Sutā Inpakuto): Koguma Skyblue performs a supercharged energy attack with the Kyu Spear alongside his fellow Kyurangers.


  • Koguma: Kyuranger Episodes 10-13, 20-22, The Ghess Indavers Counterattack, Kyuranger 23, Transformation Lessons (Special), Kyuranger 25-26, 28, 34, High School Wars Episode 4, Episode of Stinger, Kyuranger 37, 39, 40 (offscreen), 41-48, Kyuranger vs. Space Squad, Lupinranger VS Patranger VS Kyuranger
  • Ooguma: Kyuranger Episodes 10, 11, The Ghess Indavers Counterattack, Kyuranger 25, 43-44

Transformation and Roll Call

Behind the Scenes


Kotaro Sakuma/Koguma Skyblue
Shota Taguchi

Kotaro Sakuma is portrayed by Shota Taguchi (田口 翔大 Taguchi Shōta), who previously portrayed the teenage Chihiro in the second season of Kamen Rider Amazons. His suit actor as Koguma Skyblue is Naoko Kamio (神尾直子, Kamio Naoko).


  • Kotaro represents the constellation Ursa Minor and Ursa Major of the 88 constellations.
    • His name also refers to the constellation he represents: the letter, 小 (Ko) in his given name means "little", combined with the last 2 syllables in his family name 熊 (kuma) makes 小熊[コグマ] (Koguma) means "Little Bear".

The initial depiction of "Ooguma Skyblue".

  • As seen in the toy catalogue, Ooguma Skyblue was originally conceived as being a distinct form from Koguma Skyblue, having been depicted with an adult body while lacking the scarf of the former. Ultimately, the Ooguma Kyutama merely enlarges Koguma Skyblue on-screen, though the transformation sound is present in the DX Seiza Blaster.[4]
  • Kotaro brings back the concept of Rangers wearing scarves, something not seen since the earliest seasons of Super Sentai.



Icon-kyuranger.png Uchu Sentai Kyuranger
Lucky - Stinger - Garu - Balance - Champ - Naga Ray - Hammie - Raptor 283 - Spada - Shou Ronpo - Kotaro Sakuma - Tsurugi Ohtori
Transformation Devices
Transformation Controller Seiza Blaster (Dark Seiza Blaster) - Biting Transformation Gun Ryutsueder - Transformation Rotating Sword Houou Blade & Houou Shield
Multi-Use Devices
Individual Weapons and Team Weapon
Kyu The Weapon
Kyu Sword - Kyu Spear - Kyu Claw - Kyu Crossbow - Kyu Axe - Kyu Sickle - Kyu Rapier - Kyu Shot - Kyu Slasher
Other Devices
Hoshi Minato - Jiro Sakuma - Pega-san - Big Bear - Geki Jumonji - Dekarangers - Eris - Quervo - Orion - Jiiya - Aslan - Dr. Anton (good)
Mecha and Robos
Shishi Voyager - Sasori Voyager - Ookami Voyager - Tenbin Voyager - Oushi Voyager - Hebitsukai Voyager - Chameleon Voyager - Washi Voyager - Kajiki Voyager - Ryu Voyager - Kuma Voyager (Koguma Voyager - Ooguma Voyager) - Houou Voyager - Houou Station - Houou Base - Orion Voyager - Battle Orion Ship - Kojishi Voyager - Cerberus Voyager
Kyutama Gattai KyurenOh - Kyutama Gattai RyuTeiOh - Kyutama Gattai Gigant Houou - Kyutama Gattai Orion Battler - Kyutama Gattai Cerberios
Kyutama Gattai RyuTei KyurenOh - Kyutama Dai Gattai Kyutamajin - Orion Bazooka - Super Shishi Voyager - Super KyurenOh
Space Shogunate Jark Matter
Shogun: Don Armage - Don Arkage
Vice-Shogun/Akyachuuga: Tecchu - Akyanba - Kukuruga
Karō: Eriedrone - Scorpio - Magera - Thunderbird - Wunjet - Jumotsu - Desgon - Madakko - Gloven - Southern King
Executioner: Gyabler
Scientist: Dogyun - Dr. Anton (evil)
Daikaan: Gamettsui - Moretsuyoindaver - Yumepakkun - Denvil - Toome - Mamoritsuyoindaver - Megatsuyoindaver - Meshiubaindaver - Metchatsuyoindaver - Mutchatsuyoindaver - Mothma - Mondomuyoindaver - Yuterujan - Goneshi - Shaidos - Olmega - Manavil - Mediatsuyoindaver - Microtsuyoindaver - Mika Retsu - Seitokaichoindaver - Kyotoindaver - Kochoindaver
Independent Units: Geth Indaver - Ommo Indaver - Kaal Indaver
Assassins: Ikargen
Combatants: Indaver - Tsuyoindaver
Mecha: Big Moraimars - Moraimars - Moaider
Others: Deathworm - Metal Deathworm - Bossworm - Jark Sentai GoIndaver - Cow-Type All-Purpose Weapon Zero - Aslan (impostor) - Quervo
Blue Rangers
Main Series
Akira ShinmeiRyu HigashiKyousuke ShidaDaigoro OumeKin'ya SamejimaSaburo AoyamaYosuke ShimaRyuuta NanbaraYuuma OzoraBunAkiraMegumi MisakiYouhei HamaKen HoshikawaAko HayasakaDanShojiSaizouYuji MitaNaoki DomonShun NamikiGoukiNagare TatsumiAyaseKai SamezuNanami NonoYukito SanjyouHouji TomasuUrara OzuSouta MogamiRetsu FukamiRenn KousakaRyunosuke IkenamiHydeJoe GibkenRyuji IwasakiNobuharu UdoHaru TokashikiYakumo KatouSelaGaruTouma YoimachiMeltoShiguru OshikiriVroonShinichi Saruhara

Secondary Rangers
NinjamanGunmazinSignalmanIsshuu KasumiRamirezYuko FukuiKotaro Sakuma
EAGLE agentDummy Dia JackDeathdark BlueGinga BlueShadow Blue SwallowGolemPrevious TenmaRangerCopy TenmaRangerShoji's grandsonFlower Ninja AyameZokuBlueNeziBlueCopy TimeBlueCopyBlueShade GaoBlueWendinuFake HurricaneBlueFake KuwagaRaigerAyameganezumiEvil MagiBlueVrilEvil Bouken BlueKarthRyuzaburoRyujiDDai-kunNobuta-sanAmi-neesan

Power Sets
Main Series
AorengerDia JackBattle FranceDenziBlueVulSharkGoggleBlueDynaBlueBlue3ChangePegasusBlue FlashBlue MaskBlue DolphinBlue TurboFiveBlueBlue SwallowTriceraRangerTenmaRangerNinjaBlueOhBlueBlue RacerMegaBlueGingaBlueGoBlueTimeBlueGaoBlueHurricaneBlueKuwagaRaigerAbareBlueDekaBlueMagiBlueBouken BlueGekiBlueGo-On BlueShinken BlueGosei BlueGokai BlueBlue BusterBlue GorillaKyoryu BlueKyoryu CyanDeathryugerKyoryu NavyToQ 2gouAoNingerZyuoh SharkOokami BlueKoguma SkyblueLupinBlueRyusoul BlueKiramai BlueZenkai VroonSaruBrother
AkibaBlueBrave Blue DinoAoiHero