Love, Chunibyo & Other Delusions: Heart Throb

Rikka Takanashi starts living with Yūta Togashi in preparation for a second year of high school, since the rest of his family have traveled to Jakarta. Makoto Isshiki sports blond spiky hair, but Kumin Tsuyuri is uninterested. Shinka Nibutani, who has temporarily dyed her brown hair black, continues to be at odds with Sanae Dekomori. After Nanase Tsukumo tells Yūta and Rikka that the latter received three undelivered letters, Yūta and Rikka attempt to look for a new place with no avail. When Shinka, Kumin, and Sanae examine the empty apartment, Tōka finds them all and catches onto the act. After promptly defeating all five of them in a "battle", Tōka discusses with Yūta, Rikka, Shinka, Kumin, and Sanae about the current situation with Yūta and Rikka living together. Despite Tōka initially objecting to them living together, the issue is soon resolved when Kuzuha returns home for a new school semester and supervises them.

Shinka, Sanae, and Kumin conclude that Yūta and Rikka are currently living together, spying on the couple throughout the day. Meanwhile, as Rikka struggles to do household chores, Yūta notices that Rikka has spent nearly all her monthly allowance on chūnibyō collectibles. After some trouble buying groceries, Yūta and Rikka go their separate ways for a while. In the clubroom, after Yūta reveals to Shinka that he has not yet held hands with Rikka, Shinka rushes to take Yūta in order to meet her friend Kazari Kannagi, who arranges for Yūta and Rikka to go on a date on Sunday. Yūta and Rikka spend a day at the aquarium, where they hold hands. Rikka participates in a dolphin show. As Rikka states her uncertainty over what lovers should do, Yūta decides that he is fine with their relationship staying the way it is for now. Later that night, Rikka meets a peculiar girl who had moved into her old apartment, she descends from the balcony in much the same way that Yūta first met her.

Yūta is left reeling from a lewd dream about Rikka. He later ends up losing a bet against her by scoring slightly lower in a test, and he is forced to momentarily wear a magical girl outfit, much to his embarrassment. In the public announcement booth, Rikka encounters the peculiar girl from before named Satone Shichimiya, as they engage in "battle". When Yūta interrupts the "battle", he soon informs Nanase that Satone is an old friend from middle school that caused his chūnibyō outbreak back then. While walking home, Yūta finally realizes that Satone lives in the apartment above his. When Rikka later arrives home, she is surprised that Satone is invited over for dinner, since Satone's parents will be late from work. Rikka becomes jealous when Satone expresses her clinginess towards Yūta, particularly when she habitually touches noses with Yūta. After seeing Satone off, Yūta reassures Rikka by initiating a "contract" of his own.

Shinka plans to run for student council president. Due to Sanae's constant interference, Shinka urges Yūta to keep Sanae at bay, but Sanae escapes and pranks Shinka during her candid nomination speech in a classroom. At a restaurant, Yūta, Rikka, Shinka, Kumin, and Sanae chance upon Satone, who reveals that she attended the same middle school as Shinka and knew her very well as Mori Summer. The next day, Sanae is convinced that Shinka is the genuine article and starts acting more polite and affectionate towards Shinka. In fact, Sanae begins assisting Shinka with advertisements for her election campaign. When Shinka invites Sanae over to her home, Sanae shares her baked cookies, prompting Shinka to don her Mori Summer outfit in front of Sanae, much to Sanae's amazement. On the day of the election campaign speeches, Shinka's reputation backfires after Sanae reads from the Mabinogion as an endorsement speech and shows an image of Mori Summer on the projection screen. Shinka fails to get elected, Makoto becomes a dropout, and Sanae goes back to believing that Shinka is a fake, bringing their relationship back to the status quo.

The student council will determine which clubs will keep their clubrooms after school. Due to Rikka delegating a failed presentation of what the Far East Magical Napping Society Summer Thereof does exactly, this leads Nanase as the club advisor to investigate what the club actually uses the clubroom for. When Nanase points out that napping is actually a notable pastime, she suggests that the club participates in a "siesta match" against Maple Hill High School's Siesta Club to serve as an official club activity. At the train station, the club is approached by Sui Nemuri from Maple Hill High School, sparking a rivalry with Kumin. Rikka haphazardly declares that she will disband her club if they lose the match. Thus, Kumin initiates a "napping boot camp" for the club at school, though this leads Yūta to come up with the idea of them staying up all night at his apartment to be naturally tired on the day of the siesta match, yet they oversleep anyway. Upon arrival at the siesta match, Kumin encourages the others to give it their all, despite their disadvantage. They end up winning the siesta match together, allowing their club activities to continue.

It has been two months since the start of the second year of high school. Yūta, Rikka, Shinka, and Makoto go on a class trip by bus with the other second-year students to the Island of Tsukushi, where Yūta and Rikka are notably shy about their relationship. Feeling Rikka cannot handle the romance aspect well, Yūta asks Shinka to keep watch over Rikka. At night, the other female second-year students are aware that Shinka used to be Mori Summer, while the other male second-year students tease Yūta about his relationship with Rikka. Soon after, Rikka ends up sneaking into the boys' bedroom and hiding in Yūta's bed, where they almost share a kiss, until Shinka gives them the opportunity to get Rikka out safely. Before returning to the girls' bedroom, Rikka kisses Yūta on the cheek. The next day, the two go sightseeing together.

While Yūta and Rikka continue sightseeing, they come across Satone, who was separated from her own class trip after losing her purse. Yūta and Rikka manage to help Satone find it, but Yūta and Satone end up being chased by a wild monkey. When Rikka spots Yūta receiving an arcade token from Satone, she runs off feeling betrayed by Yūta and eventually coming across Shinka. As Yūta searches for Rikka, Satone contacts Kuzuha, before calling Rikka to meet up with her at a pier. Satone explains that she once fell in love with Yūta, but threw her feelings away in order to hold onto her chūnibyō persona. This leaves Rikka to question whether she intends to forever keep her chūnibyō persona and revive Yūta's chūnibyō persona. As Satone leaves, Yūta reunites with Rikka, and gives her a new umbrella and charm necklace for her birthday.

Having discovered a new website about Mori Summer, Sanae goes to a park and meets with a woman later recognized as Natsumi Tokugawa, who Sanae believes is the true Mori Summer. After Yūta, Rikka, Shinka and Kumin observe some odd tendencies from a distance, Shinka confronts Natsumi but has nothing to prove herself as the real deal. As Shinka is forced to give up the name of Mori Summer to Natsumi, Sanae begins to feel lonely with Shinka avoiding her. Yūta and Kumin notice that Natsumi has a curious infatuation for Sanae. After Yūta suggests that Shinka should challenge Natsumi to a "battle", Rikka calls upon Satone to help train Shinka at the shrine. The next day at the park, Natsumi tries to force herself onto Sanae, but Shinka recovers her chūnibyō persona to confront Natsumi, only to be overwhelmed in the "battle". However, Sanae stands to protect Shinka, feeling that the genuine article would never do the things that the impostor has done. Once being defeated by Sanae, Natsumi sadly flees after learning that Sanae's first kiss was already stolen by Shinka.

Yūta finds another arcade token from an envelope similar to the one that Satone gave him during the class trip. The next day, Kumin invites her friends to work her aunt's seaside cafe "The Nap Room". As Tōka arrives there, she introduces Cento, the daughter of her head chef in Italy. It turns out that Cento is good at swordsmanship, much to the surprise of Rikka, who gets bruised in the head with a wooden sword. That night, Yūta talks to Tōka about the ups and downs in his relationship with Rikka so far. Satone, noticed that Rikka is slowly losing her delusional powers, urges Rikka to relinquish her feelings for Yūta in order to restore her chūnibyō persona. The next day, Sanae and Cento witness Rikka and Satone initiating a "battle". When Rikka recalls the special contract that she made with Yūta, this gives birth to her new delusional powers in order to win. Afterwards, Rikka stays determined to be with Yūta and retain her chūnibyō persona. On the way home, Satone laments over the possibility of being with Yūta and retaining her chūnibyō persona.

Satone finds herself overly thinking about Yūta, particularly when she has an embarrassing encounter with him at the water park. As Tōka and Cento prepare to leave for Italy, she tells Shinka, Kumin, and Sanae something shockingly important. The next day, Shinka, Kumin, and Sanae confront Satone, confirming that she is in love with Yūta. As the Bon Festival is held that night, Rikka wanders off somewhere, prompting Yūta to look for her. Unable to find Rikka, it begins to rain when Yūta is found by Satone at the shrine. Satone is forced to fight through her own heartbreak upon learning that Yūta and Rikka have already held hands and touched noses. Yūta receives a text from Rikka requesting backup, which he interprets as her needing an umbrella. Despite her best efforts, Satone cannot hold back her tears in front of Yūta.

Back at the apartment the following day, Yūta takes care of Rikka, who has caught a cold from the previous night. Rikka has been keeping the purpose of her outings a secret, much to Yūta's worry. Satone assures Yūta, Shinka, and Kumin that she has recovered from her heartbreak, yet Shinka reprimands Yūta for being so dense while Kumin states that Shinka wants the best for her friends. Shinka as Mori Summer appears to Satone and encourages her to challenge her other inner being. On the night of a blue moon, Satone prepares to challenge Yūta, but Kuzuha informs them that Rikka has gone missing. Remembering a letter that he wrote in middle school about awakening the "Dark Flame Dragon", Yūta realizes that Rikka went off on her own many times to fulfill these instructions. Yūta and Satone find Rikka near an overhead power line, where she finds a box containing an old orthopedic cast and the third arcade token, thus affirming their love through the contract. Satone battles the Dark Flame Dragon once it is awakened, overcoming her heartbreak and becoming renewed. Back at the apartment, Yūta notices that Satone has changed, as she happily says goodbye.

Kuzuha tells Yūta that their pet cat Chimera is under the weather. As the second term of the second year begins, Rikka seems to ignore Yūta in the classroom, which brings concern to Shinka, Sanae, and Kazari. In the park, Satone informs Shinka and Sanae that Rikka is thinking about entering a superior contract with Yūta, which means the kissing phase. At a public bathhouse, Rikka, Shinka, Kumin, Sanae, and Satone bathe together. Rikka requests the others to prevent her from running away from embarrassment while trying to meet with Yūta. In the locker room, Yūta is told by Makoto, now with a dark tan, that a boy named Chihiro has a crush on him. While Shinka sends Yūta to meet Rikka at the bridge, Satone gives Rikka some encouragement. Upon Yūta's arrival, Rikka tries to get her feelings across, though still too scared to go through with it. Yūta assures her that they do not have to rush things, as she will always be the only one for him. Unfortunately, their first kiss is interrupted, when Kuzuha calls Yūta to give news that Chimera gave birth to six kittens.

Rikka becomes suspicious when Makoto allegedly gives Yūta a USB flash drive. After interrogation, Rikka, Shinka, Kumin, Sanae, and Nanase discover that the USB flash drive contains photos of a female pop star that Yūta had a crush on during middle school. A displeased Rikka instructs Yūta to return the USB flash drive immediately, though Makoto secretly lets him keep it. That night, Rikka sneaks into Yūta's bedroom and inadvertently destroys the USB flash drive in her bedroom as she falls asleep while trying to hide it from him. This leads to the two of them arguing over who was in the wrong. As Shinka, Kumin, and Sanae later realize that neither Yūta nor Rikka are willing to apologize, the girls enlist the help of Satone using a hidden camera to see how Yūta reacts when Rikka does not come home for dinner. When the girls see that Yūta left a plate of food for Rikka later on, she goes to see him and the two eventually make up with each other.

In the clubroom, Shinka Nibutani attempts to wake up Kumin Tsuyuri from the kotatsu, but Kumin seems to be constantly moving in their sleep. Shinka then meets some unexpected resistance under the kotatsu.

In the clubroom, Yūta Togashi deals with Rikka Takanashi, who puts on a second eyepatch on her left eye when she gets infected by a stye, making her spatially blind. The other girls listen from the outside when Yūta tries to apply eye drops into Rikka's eye.

One day in junior high school, Tomo was roped into helping Rikka develop her apparent abilities. Rikka used Zener cards to test clairvoyance and determined the gender of who entered the classroom to test foresight, both with negative results.

In the clubroom, Yūta, Kumin, and Makoto Isshiki witness Shinka and Sanae Dekomori playing a game of Old Maid. After ten minutes, the game reaches a climax, in which the last card is torn in half due to Sanae refusing to hand it over to Shinka, thus they both lose and continue to bicker on their way home on a rainy day.

Kuzuha Togashi deals with Yūta during his chūnibyō persona during a camping trip. While going to fetch water at a nearby stream, Yūta protects Kuzuha from chestnuts on the ground. The rest of the family later enjoys a meal of curry, but Kuzuha notices that Yūta is sitting by the campfire with a block of meat.

In the past, Shinka and Satone Shichimiya spent a day with their two friends attempting to summon an archangel via summoning circle. The paper vessel later gets blown in the sky by the wind. In the present, Satone tells this story to Kumin in the clubroom, which embarrasses Shinka.

Rikka Takanashi, Shinka Nibutani, Kumin Tsuyuri, and Sanae Dekomori play a game of word chains. Shinka repeatedly forces Rikka to come up with a phrase that begins with "shi".

After Rikka, Shinka, and Kumin wonder what is inside Sanae's hair buns, Sanae reveals a pack full of candy inside one of her hair buns to the other girls, saying that the candy is a great use of attack compared to cookies.

After Rikka states that her relationship is rather normal, Sanae begins to talk about a worthy woman. It turns out that Sanae was describing her pet lizard named Níðhöggr, supposedly a dragon of death.

Rikka, Shinka, Kumin, and Sanae, discuss their favorite flavors of hot pot, including chicken, marbled beef, medium steak, and snow crab. However, Shinka angers Sanae when mentioning a cheese fondue hot pot.

At the beach, Rikka, Shinka, Kumin, and Sanae play a second round of the game of word chains. Wanting to avenge her previous loss to Shinka, Rikka struggles in naming "cool fruits".

At the apartment, Rikka tries to figure out with Yūta and Kuzuha Togashi, as to why their pet cat Chimera has gained weight even after giving birth. They soon learn that Satone Shichimiya and Tōka have each been secretly feeding Chimera behind their backs.

After failing her English pop quiz, Rikka takes a supplementary lesson from Nanase Tsukumo in the clubroom, while Yūta, Shinka, Kumin, Sanae, and Makoto Isshiki take watch. Nanase even implements the use of "translating" the name of Rikka's umbrella, Schwarz Sechs Perfect Customize Guerzoniansus, into the supplementary lesson.