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Ephemera (イフェメラ Ifemera) is a Mayfly-like Kaiju that appeared in Ultraman Cosmos.

Subtitle: Ill-fated Baby (薄命幼獣 Hakumei Yo-ju)


Ultraman Cosmos

Ephemera building its nest out of building ruins

A baby Kaiju that never wanted to cause destruction, hatched underground nearby a building and destroyed it in order to make a nest, this called the attention of EYES. Musashi tried to summon Ultraman Cosmos but, refused, wondered why and found out when she tried to stand up and walk like a baby. Even EYES didn't want to hurt her but, JASDF commanded them to put her down so they start to shoot at her, which then made Cosmos come in and tried to hit down some of the missiles but, she thought that Cosmos was shooting at her so she attacked with lighting bolts. Cosmos got down on his knee's to plead he was not the one hurting her and not wanting to cause harm. Weirdly she stopped but, fell over her side and died! Cosmos went to investigate and finds an egg under it and discovers that this species only lives for a day! So the giant took the body to space and the egg was taken to EYES HQ to be taken care of. The Organism of Light


  • Ephemera has one of the shortest life spans for a kaiju; only for a day.
    • This behavior is also seen in insects called Mayflies, which hatch out off eggs, find mates, and after a day they lay there eggs and die.
  • Ephemera roars are modified rubber duck squeaks, monkey calls and reused Lidorias cries.


  • Length: 51 m
  • Weight: 98,000 t
  • Origin: Earth
  • Weakness: Ephemera's lifespan only lasts a day.
Powers and Weapons
  • Lightning Bolts: Ephemera can launch lightning bolts from the horns on each side of her head
  • Burrowing: After being hatched underground, Ephemera is somehow able to burrow at high speed.


Ultraman Cosmos Kaiju
Ultraman Cosmos: The First Contact Alien Baltan (Basical, Shirubyi) | Don Ron | Clevergon
Ultraman Cosmos Chaos Header | Lidorias | Chaos Lidorias | Golmede | Chaos Golmede | Spittle | Igomas | Chaos Bug | Mogrudon | Mienin | Gamoran | Small Inculas | Inculas | Yamawarawa | Geshot | Mudon | Ephemera | Waroga | Galbas | Jelga | Jirak | Chaos Jirak | Ghighi | Renki | Alien Migelon | Angrilla | Bolgils | Parastan | Chaos Parastan | Chaos Parastan S | Gelworm M | Gelworm P | Imitation Ultraman Cosmos | Gragas | Alien Srayu | Guinje | Chaos Header Iblis | Zaranga | Baby Zaranga | Eligal | Chaos Eligal | Chaos Header Mebut | Clevergon | Chaos Clevergon | Golmede Beta | Neldorand | Chaos Neldorand | Reycura | Ragstone | Mahagenom | Taildas | Chaos Taildas | Alien Beryl | Helzzking | Neldorand II | Chaos Neldorand II | Puratea | Exter Raider | Sydevakter | Delgoran | Chaos Delgoran | Sol | Taildas Mechalator | Alien Nowar | Neldorand Mechalator | Ghighi Dr. XX01 | Mugera | Alien Kyulia | GiriBanes | Waroga II | Alukela | Snow Stars | Vadata | Mazalgas | Chaos Mazalgas | Sangelu | Alien Carpcis | Arados | Ragstone Mechalator | Tablis | Mitoru | Gamoran II | Kawanoji | Gruanfan | Giragas | Alt-Helzzking | Dolba | Chaos Dolba | Eligal II | Chaos Eligal II | Chaos Darkness
Ultraman Cosmos 2: The Blue Planet Parastan | Scorpiss | Sandros | Reija | Alien Gyashi | Shirubyi
Ultraman Cosmos vs. Ultraman Justice: The Final Battle Gloker Pawn | Gloker Mother | Mienin | Lidorias | Golmede | Don Ron | Bolgils | Gloker Rook | Gloker Bishop | Alien Gyashi | Shirubyi | Giga Endra | Delacion