|This article is about a/an transformation item in Kamen Rider Den-O.|
Zeronos Cards (ゼロノスカード Zeronosu Kādo) are a transformation card item used by Yuto Sakurai, also known as Kamen Rider Zeronos. These cards allow him to access his different forms. Unlike the Rider Pass, each Zeronos Card has a limited number of times it can be used. Once a Zeronos Card's energy is depleted, it dissolves upon removal from the belt.
The Zeronos Cards are made from the memories of the older Yuto's existence. As a result, when a Zeronos card is used up, an individual who knew the older Yuto will lose those memories, forgetting him entirely. Thus, if they're completely exhausted, Yuto risks ceasing to exist in the minds of people who are not Singularity Points. He later receives a set of red Zeronos Cards from his future that use other people's memories of his younger self to change into Zero Form. These cards rust away into nothing after being used up, and cause people to lose any memory related to the younger Yuto.
Although seemingly used up at the end of the series, as more people continue to meet and remember Yuto, he begins to resupply his stock of Zeronos cards both green and red, allowing him to continue acting as Zeronos.
- Both green and red Zeronos cards have an identical yellow opposite side. With green cards, Yuto is able to use the yellow side to transform into Kamen Rider Zeronos Vega Form. It was never shown what might possibly happen if the yellow side of a red card was used however.