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 Iero Fo Shodai) of the Biomen. She was a photographer who dreamed of following in her brother's footsteps to photograph the wildlife in Africa.

Character History

Ranger Funeral

The Bioman team and Peebo at Mika's funeral.

Initially, she was hesitant to join the Bioman team. However, she was convinced when she realized that if she did not fight, then even the animals in Africa that she loved would eventually be in danger. For someone who was hesitant to do battle, Mika proved a powerful and skilled martial artist.

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. 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 to the Bioman team. Ep. 11: Enter, New Warrior Jun

In the last episode, Peebo apparently forgot to recall her for some reason in the script though Peebo remembers her during the first appearance of Silver.


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.


Akibaranger in Dead Sentai

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. Ep. 13: Delusional Collection

Super Sentai Battle: Dice-O

Yellow Four (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


  • Mika is the first female Yellow Ranger and also first female Yellow Ranger did not wear a skirt in her suit.
  • Her English dub name is Casey, which is also the name of the Red Ranger from Power Rangers Jungle Fury.
  • 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

External links


Yellow Rangers
Yumeria Moegi

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 Yellow

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