Icon-bioman.png This article is about a/an ranger in Choudenshi Bioman.

―Yellow4's roll call[src]

Mika Koizumi (小泉 ミカ Koizumi Mika) was the original Yellow4 (初代イエローフォー Shodai Ierō Fō) of the Biomen. She was a photographer who dreamed of following in her brother's footsteps to photograph the wildlife in Africa.

Character History


The Bioman team and Peebo at Mika's funeral.

During the first assault by Neo Empire Gear on Technotopia 21, he was caught in the crossfire and ran into BioRobo. Meeting Peebo, he was given a Techno Brace and became Yellow4. She shortly quit the team and walked off.Tvicon.png TV STORY-Ep. 1: The Enigmatic Giant Robo Arrives The other Biomen eventually convinced her to join them, and she became a Bioman for good.Tvicon.png TV STORY-Ep. 2: Gathering! Warriors of Destiny

Ultimately, Mika heroically took it upon herself to give her life to save her teammates, and sustained several repetitive blasts of Anti-Bio Particles from the Bio Killer Gun wielded by Mason. Following the complete depletion of her Bio Particles, Mika was then hit with powerful attacks from Psygorn, resulting in her death. The team later gave her a proper funeral while still in her Yellow4 form.Tvicon.png TV STORY-Ep. 10: Goodbye Yellow


In light of Mika's death, the Biomen were forced to search for someone who could take her place as Yellow4. They came across a female archer named Jun Yabuki and Peebo, recognizing that she possessed Bio Particles as well, recruited her into the Bioman team.Tvicon.png TV STORY-Ep. 11: Enter, New Warrior Jun

Mika was avenged when the Biomen destroyed Psygorn, and Bio Hunter Silva destroyed Mason.Tvicon.png TV STORY-Ep. 50: Assault Neograd


The footage for Bioman seen in the first episode of Turboranger ends up using clips that ultimately show both Yellow Four: the original Mika Koizumi and her replacement Jun Yabuki. This is the only compilation with multiple Sentai that show both Yellow Four from Bioman.


Yellow4 in Akibaranger.

At the end of Hikonin Sentai Akibaranger: Season Two, Yellow Four I appears with two other deceased Super Sentai warriors, Time Fire and Abare Killer, before the deceased Akagi, Yumeria, and Luna at Himitsukichi. After the Akibarangers bid farewell to Hiroyo and Kozukozu, they disappear along with the three Sentai warrior ghosts. Tvicon.png TV STORY-Ep. 13: Delusional Collection

Super Sentai Battle: Dice-O

Yellow Four as depicted in Super Sentai Battle: Dice-O.

  • Profile
Mika Koizumi/Jun Yabuki/Yellow Four: to be added

Super Sentai Legend Wars

Yellow4 is among the vast pantheon of Rangers who feature in the mobile game Super Sentai Legend Wars.


Mika is a bit of a loner at times and can be a bit stubborn, although she has a good heart it is shown despite her attitude at times Mika is loyal to the rest of the team even if at times she doesn't show it. She also has the habit of taking pictures at the weirdest times (such as when Biorobo grabbed her in the first episode) and also appears to be a bit of a UFO enthusiast.






  • Super Electronic Holography
  • Yellow Flash

Transformation and Roll Call

Behind the Scenes



  • According to Ryosuke Sakamoto, who played Red1, her departure led to the creative team taking an opportunity to show that evil is very strong and can win on occasion.
  • Mika is the first female Yellow Ranger.
  • She is also the first female Sentai Warrior to die.
  • For Mika's last episode, her voice was dubbed over by an uncredited Mayumi Tanaka as Yuki Yajima had only completed ADR for the first nine episodes before leaving abruptly.
  • With Mika appearing as Yellow4 in her Akibaranger cameo, it confirms that she is still considered a Ranger even after death, even with her replacement as Yellow4 in all later appearances including the Legend War.
  • Near the end of episode 10, Bio Robo's eyes glowed triggering her Bio Hologram to feature a footage of herself. The footage shown is her shot in the closing sequence.


See Also

  • Jun Yabuki - The Ranger who replaced her as Yellow4.
  • Trini Kwan - The first female Yellow Ranger and first female Yellow Power Ranger to be replaced.
  • Kendrix Morgan - First female Power Ranger to die while active as a Ranger.
  • Tommy Oliver - Power Ranger who similarly spent entire episodes morphed due to the absence of his actor.
  • Trini Crystal - Power Rangers counterpart in Bio-Man. See comparison page.

External links


Icon-bioman.png Choudenshi Bioman
Shirou Gou - Shingo Takasugi - Ryuuta Nanbara - Mika Koizumi - Jun Yabuki - Hikaru Katsuragi
Techno Brace - Bio Swords - Bio Arrow - Bio Machines - Bio Turbo
Bio Peace Union:
Peebo - Joy
Other Allies:
Shuichi Kageyama - Professor Shibata - Shota Yamamori - Minor Characters - Turborangers - Gokaigers
Mecha and Robo
BioDragon - BioJet-1 - BioJet-2
Neo Empire Gear
Doctor Man - Mason - Farrah - Farrah Cat - Monster - Mechaclones (Mechaclone No. 1)
Beastnoids: Zyuoh - Messerjū - Psygorn - Mettzler - Aquaiger
Mecha-Gigants: Kabuto Canth - Devil Canth - Gorilla Canth - Beetle Canth - Mummy Canth - Rhino Canth - Sea Anemone Canth - Twin Canth (Twin Dolls) - Chameleon Canth - Samurai Canth - Hammer Canth - Shark Canth - Anchor Canth (Neo Intellect Brain) - Frog Canth - Neptune Canth - Turtle Canth - Haniwa Canth - Grotes Canth (Prince) - Camera Canth - Scarab Canth - Pirahna Canth - Poison Moth Canth - Crab Canth - Ghost Canth - Spider Canth - Octopus Canth - Jellyfish Canth - Mantis Canth
Neo Mecha-Gigants: Metal Megas - Axe Megas - Skull Megas - Wrestler Megas - Magne Megas (Magne Warrior) - Cannon Megas - Battle Megas - Sonic Megas - Crush Megas - Amazon Megas - Thunder Megas - Satan Megas (Miki) - Baroque Megas - Rugger Megas - Lens Megas - Super Megas - King Megas
Anti-Bio Union
Bio Hunter Silva - Balzion
Yellow Rangers

Secondary Rangers
EAGLE agentDeathdark YellowGinga YellowShadow Yellow OwlGolemPrevious KirinRanger
Copy KirinRangerKazu's grandsonZokuYellowNeziYellowCopy TimeYellowCopyYellow
Shade GaoYellowSargainFake HurricaneYellowTensaikikkuMugiEvil MagiYellow
Evil Bouken YellowWater Pollution Minister KegalesiaYoko

Power Sets
KirengerDenziYellowVulPantherGoggleYellowDynaYellowYellow4Yellow FlashYellow Mask
Yellow LionYellow TurboFiveYellowYellow OwlTigerRangerKirinRangerNinjaYellow
OhYellowYellow RacerMegaYellowGingaYellowGoYellowTimeYellowGaoYellowHurricaneYellow
AbareYellowDekaYellowMagiYellowBouken YellowGekiYellowGo-On YellowShinken Yellow
Gosei YellowGokai YellowYellow BusterYellow RabbitToQ 3gouKiNingerZyuoh LionKajiki YellowLupinYellowKirama YellowZenkaiGaon
AkibaYellowTentoRaiger/JakanYellowYellow Hero