Kamen Rider 913 is a manga adaptation focusing on the character Masato Kusaka, supporting character in the Kamen Rider 555 series. After leaving his adoptive parents' home, Kusaka decides to go his own way. However, in this world there are beings that fight for the dominance of the planet, they are orphaned beings and suffer murders of human beings by these beings. In the midst of one of these struggles, Kusaka meets with old acquaintances from the time he did not live and also Kaixa Gear. Since then, a new story for a new driver will be started.