Katsumi Daido

"Now, enjoy your hell!"

- Katsumi's words after a battle

Katsumi Daido (大道 克己) is Kamen Rider Eternal (仮面ライダーエターナル), the main antagonist in Kamen Rider W Forever: A to Z/The Gaia Memories of Fate and before Kamen Rider W Forever film, he was the main protagonist in Kamen Rider W Returns: Eternal.

Katsumi Daido
He is the leader of the organization NEVER that uses the T2 Gaia Memories. He leads the NEVER Dopants created from the T2 Gaia Memories to attack Futo City.

In The Beginning of N/Blood and Dream, it is revealed that Katsumi was born with a congenital heart defect. This, combined with a fatal car accident, prompted his mother, Miki Daido, to use her NECRO-OVER project research, based on Philip, to save her son's life as the first Necro-Over, giving him bio-stimulants to age properly. However, despite Katsumi proving to be a skilled fighter (especially with combat knives), the Necro-Over project was rejected in favor of the Gaia Memory project, so Katsumi and his mother left the Foundation. Transforming four people who recently died into Necro-Overs, they founded NEVER. Daido is more refined and enhanced than the other Necro-Overs.

History
Katsumi and the other members of NEVER were fighting a terrorist organization in South Asia, where he encountered a Quark named Mina and fell in love with her. After a brief meeting with Jun Kazu, Katsumi gained the experimental Eternal Memory to become Kamen Rider Eternal. But when Doctor Prospect as the Eyes Dopant killed all of the Quarks, supposedly even Mina, Katsumi went mad and killed Prospect with Memory's Maximum Drive. With the Eternal Memory damaged, Katsumi discarded it and decided to wipe out the Museum.

In the film, Katsumi first appeared attacking the helicopter Tabata is riding in, taking the T2 Eternal Memory and transforming into Kamen Rider Eternal. He takes the entire case containing the T2 Gaia Memories and goes to his accomplices. But Tabata activates a switch causing the case and helicopter to explode, scattering the Memories. However, Katsumi survives, and he and his comrades search for the remaining Memories.

Katsumi then appears at the place the Riders of Futo came to meet Maria S. Cranberry, where he fights Kamen Rider Double as both FangJoker and CycloneJokerXtreme and easily overpowers both forms. He shuts down access to the pre-T2 Gaia Memories, saying that he and Philip are a lot alike, which only makes Philip more livid. After Double is defeated, NEVER claims the 19 T2 Gaia Memories that the Riders found.

With 25 of the 26 T2 Gaia Memories recovered and Phillip captured by NEVER, Katsumi reveals his plan to take over and rebuild Futo City in his image, with the people turned into Necro-Overs. Reclaiming the T2 Joker Memory from Philip's partner, Shotaro Hidari, Daido initiates the X-Bicker that will send out a wave to turn everyone into Necro-Overs, despite knowing that they will die as they are not enhanced as Katsumi is. Philip, with help from Shotaro, reactivates their Gaia Memories, and Maria injects a serum into Daido that causes him to start dissolving. In retaliation, Daido shoots Maria in the stomach and takes another serum to stabilize himself which seemed to weaken him.

They manages to catch up to Katsumi as he transforms into Eternal, but the latter escapes again. Double then catches up and fights Eternal on the Futo Tower. As he is about to deliver the final blow as CycloneJokerXtreme, Eternal seemed to regain his full strength and goes into his Strengthening Armament mode, using the Zone Memory to summon the other T2 Gaia Memories. He then uses the Never Ending Hell Maximum Drive to send Double falling from Futo Tower to his death, but through the support of the citizens of Futo and a strong gust of wind blowing into the Xtreme Memory, Shotaro and Philip transform from CycloneJokerXtreme into CycloneJokerGoldXtreme. Eternal then uses his energy to send one blast of energy at Double, but Double counters through the attack and hits Eternal with a kick strong enough to defeat him as well as destroy all 26 T2 Gaia Memories at once. With his very last breath, Katsumi remembers what death feels like.

Kamen Rider Battride War II
Katsumi Daido has been confirmed to appear in Kamen Rider Battride War II as Kamen Rider Eternal, with Mitsuru Matsuoka reprising his role. While Eternal appeared in the first Battride War game, this version was confirmed to be an entirely new, unidentified character using the Eternal Memory.

Equipment

 * Lost Driver - Transformation belt, stolen from Jun Kazu.
 * Gaia Memories - Eternal's USB-like devices that enables him in his transformation or powering his attacks. Wields only one, Eternal Memory and destroyed after it's use.
 * T2 Gaia Memory - Next generations of Gaia Memories made by Foundation X
 * Eternal Edge - Dagger/combat knife utilized by Eternal for combats

Portrayal
Katsumi Daido is portrayed by Mitsuru Matsuoka (松岡 充) of SOPHIA, who also performed W and Cod-E ~E no Angō~, the theme songs of Kamen Rider W Forever: A to Z/The Gaia Memories of Fate and Kamen Rider W Returns: Kamen Rider Eternal respectively. He would later perform the opening theme of Kamen Rider Drive, as well as voicing Kamen Rider 4 in D-Video Special: Kamen Rider 4.

As a teenager, he is portrayed by Masaki Suda (菅田 将暉), who also portrayed the lead role of Philip. As Kamen Rider Eternal, his suit actor is Jun Watanabe (渡辺 淳).