Ikari is the primary Cockroach Gaia Memory user.
He is a sociopathic dōjinshi artist who runs the Dark Bug Exterminator website, a blog where people write down the names of those they want dead and he carries out the deed as the Cockroach Dopant
With his Dopant form's speed, he steals the Luna, Trigger, Heat, and Metal Memories from Kamen Rider Double. Ikari then decided to take the rest of Double's arsenal to become more powerful.
However, after Philip learns the Heaven's Tornado dance and uses it against the Cockroach Dopant, the Gaia Memories are retrieved, allowing for the Cockroach Memory to be destroyed by LunaTrigger's Trigger Full Burst Maximum Drive.
A member of EXE, known as "C", possesses a Cockroach Memory. He transformed into the Cockroach Dopant to fight Shotaro as Kamen Rider Joker, though easily defeated by his Rider Kick
The Cockroach Dopant make an reappearance in Kamen Rider × Kamen Rider Wizard & Fourze: Movie War Ultimatum, as one of the revived members of the Monster Army that Wizard faced in his portion of the movie. He ran off when Poitrine finished off the grunts that had followed them.
Cockroach Dopant revived and part of Dai-Shocker army. Later, Rider Hunter Silva of Dai-Zangyack and Doktor G of Dai-Shocker overthrew their respective leaders and joined forces to destroy the Kamen Riders and Super Sentai. The two evil organizations united and faced off against the combined forces of the Sentai and Riders. He is seen fighting GingaYellow, TimePink, MagiBlue, and Kamen Rider Ichigou.