The members of Senkō High School's literature club become shocked when Jurai Andou, a boy usually known for his 'chunibyo' delusions, suddenly develops superpowers of his own. Six months later, each of the club members have since developed their own superpowers, which they put to the test in their monthly check-up. When student council member Mirei Kudou comes to check on the club, she ends up misinterpreting Jurai's chunibyo behavior and inadvertently reveals that she herself has developed superpowers as well. Mirei challenges the club to a superpower battle, using her own ability to steal Jurai's "Dark and Dark" ability, only to find it to be nothing more than a useless lukewarm flame. With the other members knowing not to show off their powers before her, Sayumi easily beat Mirei in a physical match. Learning that Mirei learned of the club's powers from an anonymous text, the group become curious about just who sent it.

Hatoko is invited to Jurai's house to make dinner for him and his sister, but gets downhearted when Jurai decides to stay at school to talk with Tomoyo about her writing. Hatoko gets angry at Jurai when he refuses to tell her what he talked about with Tomoyo and snaps at him, going on a rant about how she just can't understand his chunibyo behavior before running off. As Jurai goes off in search for Hatoko, he worries that he might have been putting stress on her the entire time, but Tomoyo slaps some sense into him and helps him search. Meanwhile, Hatoko comes across another Chunibyo, who teaches her not to worry about not being able to understand chunibyo, before using his own power to knock Hatoko unconscious. With Jurai having no luck in finding Hatoko, Sayumi decides to bring her Root of Origin to the next stage in order to find her.

A few weeks earlier, Hajime is seen using his "Pinpoint Abyss" ability to defeat another ability user, returning him to regular life with no memory of his ability. It is revealed that this "Fairy War" between superpower humans is for the entertainment of a group of fairies, with the last eight users standing being granted a wish. One of these fairies, Litia, informs Hajime's band of ability users, Fallen Black, that an organization known as F is fighting against the war, tasking Hajime with crushing it. While Hajime is meeting up with Jurai, his second-in-command, Hitomi Saito, leads the group in attacking F's base, encountering a mysterious girl allegedly possessing an unstoppable ability, though Hajime soon explains this girl is actually a new member known as System.

Tomoyo recalls how she first met Jurai during her chunibyo days. Meanwhile, Hatoko tries to follow a magazine's advice to get Jurai to fall for her during their vacation, though not too much success. Upon his return, Jurai invites Tomoyo to a summer festival where they talk things out and watch the fireworks together, leading Tomoyo to realise she is also in love with Jurai. The next day, Mirei, who was captured by Naoe Hagiura the previous night, summons the literature club members together and steals Hatoko's ability, using it against her.

Mirei steals Chifuyu's ability when she uses it to protect Hatoko, before Tomoyo helps everyone to escape. Regrouping at a karaoke box, the group deduce that the Mirei they fought against was an imposter possessing her body. Jurai goes by himself to confront the imposter, tricking her into stealing his enhanced "Dark and Dark of the End", which only serves to burn its user's hand with a neverending flame that cannot be extinguished. This forces the imposter to return Mirei to her body, after which they use Chifuyu's powers to chop off the burning hands and send them to another dimension whilst Sayumi heals them. Following the incident, Tomoyo and Hatoko discuss their respective feelings for Jurai, before everyone returns to their everyday lives.