The Kamen Rider Series is a metaseries of Japanese tokusatsu which generally features an insect-themed motorcycle-riding superhero who fights supervillains referred to as kaijin. The franchise began in 1971 with a show titled Kamen Rider which followed college student Takeshi Hongo and his quest to defeat the world-conquering Shocker organization. Over the years, the popularity of the franchise has grown and the original series has spawned many television and theatrical sequels. The cultural impact of the series in Japan resulted in astronomer Akimasa Nakamura naming two minor planets in honor of the series: 12408 Fujioka, after actor Hiroshi Fujioka, known for his portrayal of Takeshi Hongo/Kamen Rider 1, and 12796 Kamenrider, after the series, itself.
Although each entry in the series is different, each one shares similar traits with one and another. All generally involve at least one young adult male transforming into a Kamen Rider to fight various monsters and organizations linked to that specific Kamen Rider's origin. As the series progresses, the Rider often learns more about the monsters in the series, other Kamen Riders or the origin of his powers. Early Kamen Riders were generally based on grasshoppers, but this practice has only been done twice in the newer set of shows. Usually referred to as Rider Machines, motorcycles are an integral part of the series. Since 1971, Suzuki originally provided motorcycles for the series until Kamen Rider Agito when Honda became involved and the single Ducati featured in Kamen Rider Double. Early Kamen Riders wore scarfs along with their costumes, but this practice was dropped with Kamen Rider Black until the premiere of Double.
A trait shared among recent Kamen Riders is their ability to change forms and become stronger versions of themselves. The first power up appeared in Kamen Rider Stronger which was used by the title character. Kamen Rider Black RX had multiple forms, Roborider and Biorider. Since then, every title Kamen Rider in the Heisei era has had at least one power up with Kamen Riders Kuuga and Double having the most at 11 each within their respective series.
All Showa Riders gained their powers through some form of surgical alteration to their bodies, a practice rarely seen in Heisei Riders who are often simply "naturally" different from normal humans (imbued with mystical powers, protagonistic kaijin, etc.) or are given access to advanced technology. The nature of the Heisei Riders also varies greatly; whereas all early Showa Riders fought on the side of justice and peace, there have been numerous Heisei Riders that have fought for personal reasons such as greed, revenge, the personal enjoyment of battle, and even as antagonistic characters.