Suggested by a friend.
Jetman Graphic Novel
Released 8/30 1996
Artist: Akiko Fujii
Original Work: Saburou Yate
A sequel to the actual series, it is considered non-canon because of inconsistencies such as the Jetman having visors instead of helmets, the mecha were beynd repair in the finale, the Neo Jetman had given away their birdonic waves to the Jetmen, and Radiguet was not known to have the ability to jump into other bodies or more than one. The manga is set five years after the series ended.
The plot entails Radiguet returning for revenge using Tranza's human body and the Neo Jetman who are now in charge of defending the Earth but are pushed aside. Radiguet kidnaps the Neo Jetman and the Jetman, without the Birdonic Waves, rush out of retirement. Radiguet gains his own body and kidnaps Ryuu and Kaori's daughter Aya, transforming her into Ruma. The Jetman's new teammate Jeff (Green Eagle) makes sacrifices his new team.
Kamen Rider Spirits
Original Run: 2001 – 2009
Kamen Rider Spirits is an ongoing manga adaptation of the Kamen Rider. The focus of the story is on the original ten Kamen Riders with shifting focus on main characters. The original series ended when Magazine Z ceased publication and it was then revived in Monthly Shōnen Magazine under the title Shin Kamen Rider Spirits. It takes place after the Kamen Rider Super-1 series, Kamen Rider Spirits begins by following the lives of the original Riders in stand alone stories.
The manga then introduces the 10th Kamen Rider, Kamen Rider ZX, ignoring the events of Birth of the 10th! Kamen Riders All Together!! and make an alternate origin story. It ties up loose story ends from the various seasons, like why Tackle, was never acknowledged as a Kamen Rider. The second arc of the manga, known as Kamen Rider ZX: Forget Memories, focuses on the new Kamen Rider, Kamen Rider ZX, and also introduces the Badan Empire, the story's main villains. The third section of the manga, known as Kamen Rider ZX: Dragon Road, focuses on Kamen Rider ZX joining the original nine Kamen Riders and facing the evil Badan Empire together.
There was also a Boukenger and Shinkenger manga but I have not read any of them and its hard finding info on them so I have no idea about them.