|This article is about a/an gathering of monsters in Kamen Rider Drive.|
The Promised Number (約束の数 Yakusoku no Kazu) is the long-term goal of the Roidmudes, which will finally allow them to achieve their ambition of overthrowing the human race. Mentioned throughout the series, it is eventually revealed by Heart to be a gathering of Roidmudes who have achieved Over Evolved, with the quota being four.
Chase, designated Protozero and thus separate from the 108, was believed ineligible to join the Promised Number, as Medic reminded Heart when he was grieving over the apparent destruction of Chase at the hands of Kamen Rider Drive.
Freeze was the first Roidmude to achieve Over Evolved. However, he died with his Core following his body's destruction by Drive Type Tridoron. Soon after, Brain became the second to achieve Over Evolved and, though his body was also destroyed by Drive alongside Mach and Chaser, his Core was lucky enough to survive and escape, being begrudgingly preserved by Medic despite her hesitation to restore him due to their mutual disdain for each other. With Heart achieving his own Over Evolved, he noted that only two more were needed to be found to join himself and Brain in the Promised Number.
With 004 having gone missing, Heart believed that 006 and 008/Tornado, the latter of which was actively pursuing his Over Evolved, were the next most likely candidates. Ultimately, Tornado was destroyed by the Kamen Riders just short of achieving Over Evolved. Soon after, 006 boasted to Brain and Medic that he would be very soon achieving his Over Evolved, leaving only one more to go, with Medic vowing to become the last one. Sent by Heart to recapture the Roidmude creator, Tenjuro Banno, 006 was certain that fulfilling this objective would bring him to achieve Over Evolved. However, the overconfident Roidmude executive was swiftly killed by the scientist before he could even reveal his Evolved State. Having transfered his consciousness into a copy of the Drive Driver he created from data of the original which 004 stole for him, Banno preserved 006's body while terminating his Core and, having failed to control Medic earlier, used the now blank body to transform into his own Kamen Rider form, Gold Drive, granting a supreme power on par with Over Evolved.
Eventually, Medic achieved Over Evolved and was set to join Heart and Brain, however her body and mind were taken over by Gold Drive and he used her to get to Brain. This results in Brain going on the run, but the three of them alongside Gold Drive make up the Promised Number and they will attempt a second Global Freeze.
- 4 Over Evolved Roidmudes being needed for the Promised Number could be a reference to tetraphobia. This could also involve the Japanese belief of "four" being "death" due to wordplay (One possible pronounciation for four is "Shi" which is part of the word for "die" ("Shi-Ne").
- The sacrifice is similar to the Sabbath which was initally performed by White Wizard using four Ghoul Phantoms as magical pillars, then with four magician Riders for the perfected ritual, except one of the three Over Evolved Roidmudes needs to be sacrificed for the completion of the Sigma Circular.