This article is about a/an villain in Kamen Rider Kabuto.

"How strange. Why? Am I?"
―Rena as she dies in Daisuke's arms[src]

Rena Mamiya (間宮 麗奈 Mamiya Rena) was the human form of the Uca Worm (ウカワーム Uka Wāmu), the first executive leader Worm who posed as a woman whose childhood dream was to sing in an opera.


As a human

The original Rena was a talented singer with a kind heart that wanted to help people. She lost her memories as a Worm temporarily after being hit in the head by Hyper Kabuto's Hyper Sting attack. Believing herself to be Rena, she chases after her dream of being an opera singer until her Worm persona eventually resurfaced. During that period, she met Daisuke & they fell in love with each other. She is able to sing one more requiem for Daisuke on stage, expressing her gratitude to him. After Daisuke, as Kamen Rider Drake destroys her in her Worm form - accordingly to her wishes - she remembers her feelings for him before dying in his arms.

As a Worm

Her true form is Uca Worm, the first executive Worm. She has a large claw for the right arm capable to tearing through steel, a shield for the left arm, and has a thick shell. A cruel and clever planner, she is the one who ordered a Worm to capture (or kill) Juka. In Worm form, she is very powerful and on her first debut, she defeated both TheBee and Drake. She is also the only Worm to "truly" defeat Tendo and make him involuntarily power down. Soon after, she discovers the existence of the Hyper Zecter and attempts to retrieve it after she shoved Renge off a building, only to get caught in an explosion when the hidden bomb within the Hyper Zecter case explodes.

Video Game appearances

Kamen Rider Kabuto video game

Ucaworm is one of many Worms who appear in the Kamen Rider Kabuto video game.

Other Game appearances

Masked Rider Expansion

Uca Worm Masked Rider Expansion card

Uca Worm appears as a playable character in this trading card game with other Kamen Rider Heisei-Era , Showa-Era, super sentai,Metal Heroes and other Heroes.


Uca Worm

  • Height: 218 cm
  • Weight: 117 kg

Powers and Abilities:

  • Human Duplication: Like all Worms, they can take the form of any human they see, duplicating their memories as well.
  • Clock Up: Like all molted Worms, they can trigger Clock Up, gaining the ability to move at incredible speeds while still observing the world around them at normal speed.

Behind the scenes


  • "Uca" is the alternate name of a species of crabs known as fiddler crabs.

Concept Art



Icon-kabuto.png Kamen Rider Kabuto
Masked Rider System Users
Souji Tendou (alternate) - Arata Kagami - Daisuke Kazama - Tsurugi Kamishiro - Sou Yaguruma - Shun Kageyama - Souji Kusakabe
Movie-exclusive Riders: Issei Kurosaki - Hidenari Oda - Tetsuki Yamato
Gear: The Zecters - Rider Belt - Rider Brace - ZECT Kunaigun - Kabuto Kunaigun - Drake Glip - Zectmizer - Perfect Zecter - Gatack Double Calibur - Sasword Yaiver - Kabuto Extender - Gatack Extender - Machine Zectron - Kabutick Zecters
Hiyori Kusakabe - Jyuka Tendou - Yumiko Takemiya - Gon - Jiiya
Other allies: Takeshi Hongo
Riku Kagami - Masato Mishima - Renge Takatori - Yuzuki Misaki - ZECTroopers
The Natives: Daigo Tachikawa - Shuichi Tadokoro - Negishi - Masato Mishima - Hiyori Kusakabe
Worms: Aracnea Worms (Aracnea Rubor - Aracnea Flavus - Aracnea Nigritia) - Lanpyris Worm - Bellcricetus Worm - Epilachna Worm - Pulex Worm - Verber Worms (Verber - Verber Rota) - Coleoptera Worms (Coleoptera Aeneus - Coleoptera Croceus - Coleoptera Argentum) - Musca Worm - Sectio Worms (Sectio - Sectio Acuere) - Formicaalubus Worms (Formicaalubus - Formicaalubus Oculus - Formicaalubus Maxilla) - Brachypelma Worms (Brachypelma Aurantium - Brachypelma Viridis) - Tarantes Worm Purpura - Geophilid Worms - Acarina Worms (Acarina - Acarina Amber) - Viella Worm - Sepultura Worm - Genomyas Worm - Culex Worm - Foliatus Worm - Cammarus Worm - Camponotus Worms (Camponotus Oculus - Camponotus Maxilla) - Cochlea Worm - Leptophyes Worm - Subst Worm
Executive Worms: Uca Worm - Cassis Worm
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