Yuki Yuna Is a Hero

Heroes' screams echoed out into the heavens.

There was something written in a certain diary.

Yuuna and the Hero Club work very hard.

Finally, the climactic battle has begun. The heroes are fulfilling their roles with full of new powers. The flowers bloomed beautifully. What kind of destiny would await them in the future...

The WaSuYus are going to their elementary school's class trip. The three of them are put in a crisis because of the Vertex's advanced action whom appeared as if to shatter their fun daily life.

The WaSuYus haven't been able to unify because they haven't had much time to prepare. So, they decided to choose a leader and strengthen their unity by doing a training camp. Sumi saw herself as the leader, but Aki-sensei appointed Sonoko as the leader...

Yuna is forced to fight against Mimori, who can't bear to lose her memories of everyone like she did with Sonoko, or be forgotten about herself. However, Yuna states her determined feelings to never forget about Mimori and manages to stop her. With the Vertex's final attack headed for Shinju, all of the girls, despite the afflictions caused by their Mankai forms, band together to block the attack, with Yuna delivering the final blow just in time, after which their fairies disappear, ending their role as heroes.

Mimori recalls the events following the loss of her memories, including her first meeting with Yuna and how they came to join the Hero Club. Having discovered her legs and memory were lost because of the Mankai form and that everything from her standard of living to moving near Yuna was arranged by Taisha, Mimori once again approaches Sonoko, who tells her the true nature of the world. Investigating a hidden barrier facing opposite the Shinju, Mimori goes inside to discover a hellish landscape filled with smaller Vertexes that are rebuilding the ones that were already defeated, dooming the heroes to continue battling until they become completely disabled. Not wanting the others to suffer like Sonoko did, Mimori believes the only solution is to destroy Shinju and blasts a hole in the barrier, unleashing several smaller Vertexes into the forest.

After Fu informs the others that their battle isn't over yet, with each girl besides Karin receiving an additional fairy, the girls soon come up against another forestization. Discovering the remaining Vertex, finding it to be overflowing with cores, Yuna quickly disposes of them using the power of her new fairy, causing some worry amongst her friends. When the forest disappears, Yuna and Mimori end up separated from the others, having been summoned by a hospitalized girl, who reveals herself to be a former hero named Sonoko Nogi. Sonoko reveals to them the secret of the Hero System, in which heroes permanently lose the use of a bodily function in exchange for the power granted by the Mankai form, further revealing that heroes are effectively sacrifices to Shinju who can never die. On top of the shock both girls feel upon hearing this, Mimori is also saddened as she seems to know Sonoko, but is unable to remember her.

After receiving checkups at the hospital following their battle against the Vertex, Fu is revealed to have lost some vision in her left eye while Itsuki has lost her voice, both of which they assume to be temporary symptoms caused by battle fatigue. However, upon discovering Yuna has also lost her sense of taste and that she herself has gone deaf in her left ear, Mimori fears that these symptoms could be a side-effect of the Mankai form and gets in touch with Fu about it. Meanwhile, Karin, who hasn't been affected since she didn't use the Mankai form, has been avoiding going to the clubroom, as she fears she no longer has any purpose now that the Vertex are gone. However, Yuna manages to find her and convince her that, even with no-one to fight, the Hero Club will still carry on like it always has. Touched by Yuna's friendship, Karin convinces Taisha to let her stay at Sanshu Middle School until graduation, while the girls make plans for summer break.

Itsuki, who gets nervous when singing in front of others, is anxious about an upcoming test, so the Hero Club decide to go to karaoke to help boost her confidence. Meanwhile, Fu is unnerved by a message from Taisha telling her to expect the worst. As she continues to struggle with her nerves, Itsuki thinks about the burden placed on Fu, who has been looking after her ever since their parents died. Later, as Fu laments getting Itsuki involved with the Vertex, Itsuki assures her that she feels happy being able to fight alongside her. On the day of her test, Itsuki finds a letter from everyone encouraging her to do her best, allowing her to sing with confidence and giving her a goal of becoming a singer. Soon afterwards, as Fu contemplates with worst case scenario, another forestization appears.

With the Vertex able to regenerate its wounds, Fu has Yuna and Itsuki perform a sealing ritual in order to expose its core. Working together, Fu and Yuna manage to destroy the core, defeating the Vertex and returning everyone to the real world. The next day, Fu explains that she was tasked by her organisation, the Taisha, to grant hero candidates the power to fight against the twelve Vertex that threaten Shinju. Mimori, frustrated that she couldn't help everyone during the battle, directs her anger at Fu for keeping things a secret from everyone, but Yuna manages to cheer up a little. The girls are soon brought into another battle as three more Vertex emerge, using combined attacks to keep them from performing the sealing ritual. When the Vertex start attacking Yuna, Mimori becomes determined to protect her and awakens her hero form, using long range attacks to provide support, and together they manage to defeat all three Vertex.