Matsutaro Okumura is the synchronization partner of the Cook Roidmude and a minor antagonist in Kamen Rider Drive.
the head chef of the French restaurant Suprême, Matsutaro Okumura fell in love with the human form of Roidmude 090, Miho Masukawa, which 090 exploited to get Okumura to synchronize with her to evolve into the Cook Roidmude. The Cook Roidmude was then tasked by the Medic Roidmude to perfect the Honfleur's Dusk recipe so it could be used by the Heart Roidmude to achieve his Super Evolution.
Cook tested the recipe on a handful of Roidmudes but all of them combusted due to the sauce being incomplete. Eventually though, the Cook Roidmude perfected the Honfleur's Dusk, with Medic giving Cook an arm cannon as a reward to help him in his battle against the Kamen Riders. Despite this, Cook was defeated by Kamen Riders Drive, Mach and Chaser, separating the synchronization and the destroying 090's Core, causing Matsutaro to become depressed over the loss of his love.