Vividred Operation

In the near-future, the world's energy problems have been solved thanks to a scientific power known as the Manifestation Engine which provides energy from the sky. On the island of Izu Oshima, Akane Isshiki is living a simple life with her sister, Momo, and her grandfather and creator of the engine, Kenjirou. As Akane eagerly awaits the arrival of her classmate, Aoi Futaba, who is travelling to the nearby Blue Island for treatment, she and Momo hear an explosion coming from their home and discover that Kenjirou has somehow switched bodies with an inanimate ferret doll as the result of an experiment. Undeterred by his new form, Kenjirou gives Akane his latest invention, a strange key, in order for her to fight against a strange alien mech, known as an Alone, that is attacking Blue Island, where the Manifestation Engine is stored.

As Kenjirou instructs Akane and Aoi to undergo 'docking', Aoi receives her own Ignition Key, allowing her to also transform using the Vivid System. Receiving weapons to go along with their new abilities, Akane and Aoi begin fighting against the Alone whilst protecting the innocent. Meanwhile, Kenjirou contacts the head of the Manifestation Engine's management bereau, Yuuri Shijō, in order to gain military support in assisting the girls in fighting the Alone. After knocking out the Alone's core, stopping its movement, Akane and Aoi attempt the Docking Operation, but it fails due to one of them subconsciously rejecting the fusion. As Aoi worries that she might be the one causing it to fail, she thinks back to when she first became friends with Akane, who gave her a tomato on their first meeting. Meanwhile, a mysterious girl fires a glowing arrow into the Alone, bringing it back to life and changing it into a more powerful form.

As Akane, Aoi and Momo begin their first day to New Oshima Academy, Akane, who was using the Vivid System as she was running late, ends up meeting kendo club member Wakaba Saegusa, who becomes shocked when she counters her attack. After Akane and Aoi officially transfer into Wakaba's class, Wakaba chases after Akane demanding a rematch until she ends up bumping into Momo, deciding to take her to the nurse's office. As Wakaba and Momo get acquainted, Akane overhears how Wakaba wanted a rematch to prove she's the strongest. After her dad tells her to think about what 'true strength' is, Wakaba formally challenges Akane to a serious kendo match, which reminds Wakaba of how fun kendo used to be for her. Just then, their match is interrupted by the appearance of a serpent-like Alone. As Wakaba comes to realise what true strength is from watching Akane and Aoi fight, she asks to fight alongside them, granting her her own ignition key.