Katsumi Daido

Kamen Rider Eternal (仮面ライダーエターナル) is a Kamen Rider. He is the main antagonist in Kamen Rider Double 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 is played by SOPHIA vocalist, Mitsuru Matsuoka.

Katsumi Daido
Katsumi Daido 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 Fuuto City.

In The Beginning of N/Blood and Dream, it is revealed that Katsumi was born with a congenital heart defect. As a result, combined with a fatal car accident, his mother, Miki Daido used her NECRO-OVER project research, based on Philip, to save her son's life as the first Necro-Over while 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. Recruiting four people who recently died and became Necro-Overs and founded NEVER. Unlike his comrades Daido is more refined and enhanced than the other Necro-Overs.

Story (Kamen Rider W Returns: Eternal)
Katsumi along with 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 and 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.

Story (Kamen Rider W Forever)
In the film, Daido 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 proceeds to go to his accomplices. But Tabata activates a switch causing the case and helicopter to explode, scattering the Memories. However, Daido survives and he and his comrades search for the remaining Memories.

Katsumi then appears at the meeting place the Riders of Futo came to meet Maria S. Cranberry where he fights against Kamen Rider Double as both FangJoker and CycloneJoker Xtreme and easily overpowers both forms, while shutting down access to the non-T2 Gaia Memories and saying that he and Philip are a lot alike, which only makes Philip angry. After Double is defeated NEVER claims the 19 T2 Gaia Memories the Riders found.

When 25 out of the 26 T2 Gaia Memories are recovered and Phillip is captured by NEVER, he reveals his plan to take over and rebuild Futo City in his very own image with the people turned into Necro-Overs. When reclaiming the T2 Joker Memory from Philip's partner, Shotaro Hidari, Daido initiates the X-Bicker that will send out a wave that will turn everyone into Necro-Overs knowing that they will die as they are not as enhanced like Daido is. Philip with help from Shotaro reactivates their Gaia Memories and Maria arrives injecting a serum into Daido that causes him to dissolve away. Daido in retaliation shoots Maria in the stomach and takes the serum to stabilize himself.

Double manages to catch up to Daido as he transforms into Eternal but escapes again. Double then catches up and fights Eternal about to deliver the final blow as CycloneJoker Xtreme. But Eternal goes into his Strengthening Armanent mode by using the Zone Memory to summon the other T2 Gaia Memories. He then uses the Never Ending Hell Maximum Drive to kill Double but he comes back later as CycloneJoker Gold Xtreme. Eternal uses his energy to send one single blast of energy at Double but Double counters with Golden Xtreme going through the attack and Eternal. With his very last breath, Katsumi remembers what death feels like.

Lost Driver
The Lost Driver is a second generation Memory Driver belt originally used by Kamen Rider Skull. To transform Daido puts the T2 Eternal Memory into the Memory Slot and undergoes the transformation.

Maximum Slots
In addition to the Maximum Slots on the Lost Driver and the Eternal Edge, Kamen Rider Eternal Blue Flare has a series of Maximum Slots on belts around his chest, right arm, and left leg, for a total of 26 for every T2 Gaia Memory.

Gaia Memory

 * Eternal Memory: The original Eternal Memory is similar to it's T2 counterpart albeit imperfect, simply preventing movement for users of T1 Gaia Memories. When used by incompatable users, the Memory only allows access the Red Flare form. Jun Kazu even commented that when he recieved the memory, he was told it was a "fickle Memory" However, for more compatable users like Katsumi, they can access the Blue Flare form. After Eternal was able to defeat Eyes Dopant, the original Eternal Memory was damaged, as it was simply a prototype, and Katsumi decided to discard it, saying that he would find the Memory again.
 * T2 Eternal Memory: Kamen Rider Eternal's primary Gaia Memory, used for the transformation and Maximum Drives. This unique Gaia Memory has power over other Gaia Memories, neutralizing the original Gaia Memories use and allows Eternal to access the power of the other T2 Gaia Memories without transforming with them.
 * T2 Unicorn Memory: One of the 26 T2 Gaia Memories. Used to create an energy drill around his fist for a Rider Punch Maximum Drive. He used only this memory once to defeat Kamen Rider Joker.
 * T2 Zone Memory: One of the 26 T2 Gaia Memories. Used to gather the other T2 Memories in one place when placed into the Maximum Slot on the Lost Driver.

Eternal Edge
The Eternal Edge (エターナルエッジ, Etānaru Ejji) is Eternal's primary combat knife that is summoned through the powers of the Eternal Memory. When the Eternal Memory is placed in the weapon's Memory Slot it initiates the Eternal Requiem Maximum Drive which disable the original Gaia Memories. It also has the unseen Bloody Hell Blade Maximum Drive.