Kamen Rider W Forever: A to Z/The Gaia Memories of Fate

After picking up the T2 Gaia Memories from fellow Foundation X agent Jun Kazu, Tabata leaves Futo via an Apache helicopter to his group's base of operations. Unbeknownst to him, he is being tailed by a Hercules cargo plane before a young man leaps out of it and into the helicopter. The man takes the briefcase and uses the T2 Gaia Memory with the letter E to transform into a caped Kamen Rider as Tabata activates the suitcase's self-destruction function. Surviving the blast as it causes the helicopter to explode, the rider lands back in cargo plane where his accomplices are waiting as the other 25 T2 Gaia Memories to rain down on Futo. They head off to find the Gaia Memories as their leader intends to turn the city into hell on Earth.Sometime later, as rain has postponed the Futo Fireworks celebration which he and others were to attend, Philip is in a nearby park reading a book from the Gaia Library. Seeing a mother and her son Eita, he feels a bit sad since his last encounter with Shroud and is curious about mother/child relations. Soon, Philip sees the IceAge and Violence Dopants attacking people, surprised as their Gaia Memories were destroyed in the past. He holds them off until a woman who reminds him of Shroud arrives and to support him before Shotaro arrives. As they form Kamen Rider Double to fight the IceAge and Violence Dopants, Kamen Rider Accel defeats the Nasca and Weather, finds their unbroken Gaia Memories to be of the same design as their own. In Double's fight against the other two Dopants, assuming LunaJoker to fight them, he witnesses mysterious green Dopant saving the mother and child from debris caused by the fighting before defeating his opponents with the Joker Strange Maximum Drive. The two Dopants turn out to be Watcherman and Santa-chan who explain they found the Gaia Memories which forcefully entered their bodies before the mystery woman reappears and introduces herself as Maria S. Cranberry, an Interpol Agent. Back at the office, Maria explains to the Narumi Agency and Ryu that the Gaia Memories are T2 Gaia Memories, which are refined versions of the T1-type Gaia Memories. Furthermore, the raining of Memories cross the city is the work of a terrorist group led by Katsumi Daido. As Philip is perplexed with Maria, thinking she is Shroud and visiting her hotel room with a music box he found that belongs to her, the others go out to find the T2 Gaia Memories.When Shotaro goes to his informants Queen and Elizabeth, Elizabeth reveals that she has found the T2 Accel, Key, and Bird Memories through their high school connections. Queen also reveals that she has found the T2 Queen Memory, throwing it into the street when it tries to take her over. But a female motorcyclist, Reika Hanehara, picks up the Queen Memory as Shotaro attempts to talk her out of using it. However, Shotaro realizes Reika is one of the terrorists as she presents the T2 Heat Memory, using it to become the Heat Dopant and driving off as Shotaro pursues as Double on the HardBoilder. However, it turns out to be a trap as the effeminate terrorist Kyosui Izumi becomes the Luna Dopant with the T2 Luna Memory to conjure Masquerade Dopants. Double deals with the fake Dopants before using the Trigger Aero Burst Maximum Drive to destroy the Heat Dopant's bike. He fights Heat Dopant being ambushed by the muscle man Gozo Domoto, knocking him into the T2 Metal Memory as he uses it to become the Metal Dopant. Double is overwhelmed by the three Dopants until the mysterious green Dopant appears and spirits the Kamen Rider to safety. Back at the agency, after Philip uses the Gaia Library to confirm the terrorists are actually the members of "NEVER" or "Necro-Over", undead super soldiers developed by Foundation X. Looking over 19 of the T2 Gaia Memories, Philip gets an urgent call on his Stag Phone from Maria, requesting that they bring all of the Gaia Memories they have found to the Futo Tower construction cite. However, it turns out to be a trap set up by Daido as he transforms into Kamen Rider Eternal.Enraged with the villain calling himself a Kamen Rider, Shotaro and Philip transform into Kamen Rider Double FangJoker to fight Eternal. Ryu as Accel when he is attacked by NEVER's sniper Ken Ashihara before he uses the T2 Trigger Memory to transform into the Trigger Dopant. Even when Shotaro and Philip transform into the CycloneJokerXtreme form, they and Accel are powerless against their respective opponents. Deciding to end this quick, Eternal activates his Eternal Requiem Maximum Drive, negating all non-T2 Gaia Memories and leaving the other Kamen Riders powerless. Though Maria uses the T2 Cyclone Memory to become the green Dopant, the Cyclone Dopant, to save Akiko from the Trigger Dopant, she gives Eternal the group's T2 Gaia Memories to NEVER while giving Philip a message. By then, NEVER finishes turning Futo Tower into their base of operations while installing their greatest weapon: the X-Bicker. The next day, as the gang takes refuge in the woods to recover from the battle, Ryu picks up a television broadcast on his Beetle Phone and the gang learn that NEVER is offering a billion yen and membership to anyone who finds and hands them the last T2 Gaia Memory that they are missing: the J Memory. This in turn causes anarchy with anyone with a Gaia Memory trying to come forward to claim the reward. To make matters worse, Shotaro and Philip fight over if Maria can still be trusted, causing an irked and confused Philip to run off to find Maria. Finding Maria at a music hall, Philip begged to know if she is Shroud before Daido appears and reveals Maria to be his mother before knocking a devastated Philip out after learning that Maria set him up.Returning to the agency, Shotaro fumes over Philip's behavior when Kamen Rider Skull appears in the office who helps Shotaro realize Philip's feelings about wanting a family before leaving his Lost Driver and disappearing. Shotaro walks over to inspect the Lost Driver when Reika appears in the office to kill him. After learning that Daido has Philip, Shotaro tries to fight back before she transforms into the Heat Dopant and sends flying over his desk when he finds a hole in the floor and finds the object that made the hole in his ceiling earlier: The T2 Joker Memory. Using it, Shotaro transforms into Kamen Rider Joker as they take the fight to a nearby creek where the Heat Dopant can no longer use her fire-based attacks effectively. Joker uses the opportunity to use his Rider Kick Maximum Drive on the Heat Dopant, knocking her out. With Ryu's support, Shotaro heads to Futo Tower to save Philip and defeat NEVER, attracting Luna Dopant's attention as he sends his Masquerade Dopant illusions to attack Shotaro as he transforms into Joker and gets into the tower, while Ryu manages to use the Engine Blade to hold off the Dopants as well as Izumi and Ashihara. Facing the Metal Dopant, Joker manages to use his Rider Punch Maximum Drive to defeat him before arriving to NEVER's control center with Philip hooked up to the X-Bicker as an amplifier. Eternal overwhelms Joker and takes the final T2 Joker Gaia Memory as he uses T2 Zone Memory to summon all T2 Gaia Memory into the X-Bicker to activate the device which will send out a wave of energy that will turn everyone into Necro-Overs. By then, Reika arrives, begging for help as the body is falling apart with Daido pushing her aside, revealing that when a Necro-Over is hit by a Maximum Drive they will crumble away into dust, as Domoto dissolves away outside with Reika following after realizing how heartless Daido is.Refusing to let Daido have his way and with Shotaro covering him, Philip deactivates the X-Bicker by force and disable T2 Eternal Memory's Eternal Requiem. Though Shotaro is unable to hold him back for long, Daido is disabled when Maria injects him with an anti-Necro-Over solution. Enraged, Daido shot her in the stomach as Philip destroys the X-Bicker while Ryu becomes Accel to defeat the Trigger Dopant in Trial form. As Daido limps off to inject himself with the antidote, Maria apologizes to Philip for using him and causing all the chaos as he assures her that he'll stop Daido. Managing to find Daido, Shotaro and Philip fight Eternal before Transforming into Double. However, the Luna Dopant arrives to drag Double off. However, before the fight could start, a strange red coin rolls up to Double's foot. Double picks it up as a young man named Eiji Hino appears and decides to fight the Luna Dopant, using two other coins to transform into Kamen Rider OOO and hold the Luna Dopant at bay as Double goes after Eternal. Switching from Tatoba Combo to his Takakiriba form, OOO destroys the Dopant with his Medajaribur. Using the HardTurbuler, Double catches up to Eternal at the top of Futo Tower as he was about to use the X-Bicker energy to destroy the city, fighting the evil Kamen Rider in his 9 basic forms before transforming into CycloneJokerXtreme to deliver a final blow. However, Eternal uses the Zone Memory once more to summon every T2 Gaia Memory onto his Memory Slots, increasing his power. Eternal activates his Never Ending Hell Maximum Drive, absorbing the X-Bicker energy as he sends the blades of the Futo Tower onto Double, sending him to his death. But at the last second, with the city's support of Double, a gale blows through Futo and into the Xtreme Memory, transforming CycloneJokerXtreme into CycloneJokerGoldXtreme. With this power boost, Double flies through the debris towards Eternal, hitting him with the Golden Xtreme Maximum Drive Rider Kick. In his last breath, Katsumi Daido laughs, stating that he hadn't been feeling his own death for quite some time before exploding in a massive fireball, with the Eternal Memory breaking soon after. Later, everyone celebrates the defeat of NEVER, watching the fireworks as repairs with Futo Tower begin.After the end credits a mysterious person in bandages is seen in a bathroom.

Question: What postpones the Futo Fireworks Celebration?
Answer: Rain