Time Travel

Time Travel is the process of traveling through different points in time. This concept is featured in many Kamen Rider series.

Time Vent
In both the main Ryuki series and Decade's World of Ryuki, the card Time Vent allows its user send himself or someone else back in time. This person usually seems incapable of significantly altering the flow of time they encounter as they live back to the present, as Shinji Kido discovers much to his dismay.

Hyper Zecter
In Kamen Rider Kabuto, Kamen Riders transformed into Hyper Form using the Hyper Zecter can move faster than light, therefore they can travel into the past. The Hyper Zecter itself is also capable of traveling through time. This allows it to be used by more than one Rider, as seen in the non-canon Kamen Rider Kabuto Hyper Battle Video, or to continue being used even after it is destroyed, such as in its debut episode.

Time Travelling Trains
In Kamen Rider Den-O, DenLiner, Zero-Liner, New DenLiner, Ghost Train, GaohLiner, Nega DenLiner, as well as KingLiner can be used to travel through the time stream, though usually only to specific points where a Rider Ticket points to (this, however, may be more down to choice by Owner's rules than the trains' actual capabilities, as seen in Den-O's finale). The Battleship Onigashima also has this ability.
 * After riding on a time travelling train, the passenger would become a Singularity Point, which basically protects them from any temporal effects in the past. While only some humans like Ryotaro Nogami already possess this ability, Eiji Hino and Ankh became one the moment they stepped foot onto the DenLiner..

Imagin Contracts
Also in Den-O, after fulfilling the contracts made with their contract holders, the Imagins can open their host's body to go into the past to the point of their most intense memory. Kai is also capable of opening himself up as a time portal for an Imagin to any point in his own past without need for a contract to be made and fulfilled.

Castle Doran
In Kamen Rider Kiva, Castle Doran can open a Time Door to summon or send any person from or into any moment in the past. Castle Doran itself can enter the time stream.

Time Ring
Kamen Rider Wizard can use the Time Ring to open a time portal that connects to another point in time.

Time Road
In Kamen Rider Drive, Paradox uses this machine to travel from 2035 back to 2015 in order to destroy Krim Steinbelt and bring forth a dystopian future ruled by the Roidmudes.

Time Majin
In Kamen Rider Zi-O, Tsukuyomi uses the Tima Majin to travel from 2068 back to 2018.

Other cases

 * The very first case of time travel and the only one to occur in the Showa era was in Kamen Rider Black, where Golgom's Cobra Mutant possessed a device that allowed him to travel through time.
 * The Evil Eye in Kamen Rider: Seigi no Keifu possesses the power to disrupt the natural flow and merge certain points of time, bringing Kamen Riders of several eras together.
 * In finale of Kamen Rider Kiva, Masao Kurenai (future Kamen Rider Kiva) and Kivat-bat the 4th travel back in time to the present day (2009) from 2031 to fight alongside their predecessors against the Neo-Fangire, who have also come from 2031.
 * In Cho Kamen Rider Den-O & Decade Neo Generations: The Onigashima Warship, an earthquake in 1980 causes a time crack, allows Mimihiko to go through.
 * In Cho Kamen Rider Den-O & Decade Neo Generations: The Onigashima Warship, Tsukasa Kadoya and Daiki Kaito somehow travel to the past by using their Dimensional Wall.
 * The space-time police force in Kamen Rider × Kamen Rider × Kamen Rider The Movie: Cho-Den-O Trilogy Episode Yellow has their own method of time-traveling.
 * In Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals, Gara used a device empowered by the desire energy collected by the Bells to warp time over three locations as part of his plan.
 * In Kamen Rider × Kamen Rider Fourze & OOO: Movie War Mega Max, a time crack was opened when a meteor landed in Japan, connecting the present to the point of 40 years in the future. This time crack collapses after Kamen Rider Aqua and future Ankh return to the future, but was briefly opened again by Aqua to distribute Super Core Medals to Kamen Rider OOO.
 * Eel has the ability to open a time portal.
 * In , Saburo Kazeta somehow travels back in time to help his future teacher.
 * In Kamen Rider Gaim, Mai Takatsukasa, the Woman of the Beginning, used power of the Forbidden Fruit to go back to the past in an attempt to change the history. However, according to DJ Sagara, whom can also enter the time stream, the structure of time itself is so complicated that not even the nigh-limitless power of the Golden Fruit can properly control traveling through it. As a result, she herself gets lost in multiple parallel timelines.
 * In Kamen Rider × Kamen Rider Ghost & Drive: Super Movie War Genesis, Ryu Tenkuji in 2005 somehow was able to open a wormhole to the Monolith in the basement of the Daitenku Temple in 2015 to bring his son in the past. When dying, he opened another wormhole to return his son and his friend to the present.