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

Rena Mamiya (間宮 麗奈 Mamiya Rena) is 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. Believing herself to be Rena, she chases after her dream of being an opera singer until her Worm persona eventually resurfaced. She is able to sing one more requiem for Daisuke on stage, expressing her gratitude to him.

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 Tendou 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.


  • Height: 218 cm
  • Weight: 117 kg


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

Video Game appearances

Kamen Rider Kabuto video game

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