Volume 1
Volume 1 focuses on the FMC and MC getting together. When Amada (from now on POS) gathers his harem, they try to make the MC and Amada get along. The MC has no intention of doing so, realizes Amada was the mastermind behind his torment, and decides to openly wage war against him.
He counters every heroine (plus Tsukiyama, the best friend) individually. POS rushes his plan and tries to incriminate the MC early, but the MC—being big-brained—saw it coming and developed countermeasures, mainly swapping bags with Tsukiyama to ruin the setup. POS throws the heroines under the bus and tries to play innocent, but FMC exposes him; POS trying to punch her doesn't help his case either. POS then leaves the school due to "sickness."
The heroines are shamed and left alone, but the MC, being the good guy he is, helps them in different ways, forming a new group with them (except the heroine in the MC's class, who dips hard and stays with her new friend group; she will be referred to as Koro).
Volume 2
A new heroine is introduced: a childhood friend who is also a famous VTuber (VTuber from now on), who transferred schools due to a stalker. Originally, the MC tries to help her and confides in her that POS is indeed a POS. She doesn't listen and reunites with POS instead. POS returns to school, apologizes to everyone, and heroines Glasses and Cow (the sporty one) join his side again.
The MC tries to help VTuber, thinking the stalker issue stems from an information leak at school involving FMC's friend—who is also a VTuber and allegedly sold out info to VTuber's stalker—but things don't add up. The MC runs into VTuber while shopping and sees her with the "stalker" who was apprehended in his first life. POS tells the MC he will change schools to avoid further conflict, but the MC realizes POS is plotting something with VTuber again. He figures the target is now the FMC: POS wants to frame her for leaking info to the stalker, force her to transfer, and then join her later to start their rom-com.
Things go almost as planned until POS shows his hand. The initial target was indeed the FMC, but when the MC took steps to disable the plan, POS pivoted and tried to use the MC's sister instead. POS claims that if the MC cuts all contact with FMC and FMC transfers, he won't release his evidence. However, this becomes moot when it's revealed Glasses and Cow never actually changed sides—they joined POS to help the MC and obtained evidence of the stalker talking normally with VTuber. POS once again dips on VTuber and gets beaten by the MC. VTuber finally realizes POS is a POS after he tries to woo her again once she is left alone.
It is revealed that Glasses is devoted to making the MC happy after she starts having dreams of what happened in the first life. She deeply regretted her past actions and was horrified by the consequences. In that timeline, she had asked POS to help the MC, but POS ignored her. She then avoided POS out of fear until she saw the MC on the roof and rushed to stop him—arriving too late. Seeing this, the FMC told Glasses to disappear. The FMC committed suicide three days later, and Glasses did the same a week after.
Volume 3
This volume focuses on Tsukiyama being an absolute Bro (no Tsukiyama slander will be tolerated; the dude is a ride-or-die). In the past life, he actually tried to help the MC and never gave up on him. However, after being framed as arrogant and shallow, his popularity tanked and he was too ruined to help. His father owns a conglomerate that employs the MC's dad. Tsukiyama tried to introduce the MC to his father, but the MC was too hurt, and Tsukiyama was too inept to convey things properly. POS went to Tsukiyama's dad and lied, claiming the MC was bullying Tsukiyama, which got the MC's dad fired. When the MC's dad died in an accident, Tsukiyama tried once more to reach the MC, but the MC refused to listen, leaving Tsukiyama standing outside in the rain.
In the second/current life, the story focuses on Tsukiyama feeling lonely despite being surrounded by people. He regained his popularity, but he can't trust anyone since everyone abandoned him after the events of Volume 1. He tries to organize a study group at his house to introduce his friends (mainly the MC) to his father, but the MC—being his usual awkward self—refuses every time, making things uncomfortable.
Meanwhile, a subplot unfolds where Koro is harassed in the classroom by two guys. Another classmate takes the blame and blackmails Tsukiyama, threatening to tell his father that he is actually a loner. Tsukiyama tries to get the MC's attention by inviting him to study groups; when that fails, he tries antagonizing the MC and half-heartedly wooing the FMC. The MC uncovers the plot and reveals that Tsukiyama was intentionally acting out so everyone would hate him, allowing him to be left alone and stay with the MC's group where he felt appreciated. In the end, the blackmailing classmate is beaten up and handed over to VTuber as free manpower. Tsukiyama and the MC patch things up and become besties. Tsukiyama gets invited to meet the MC's family, proud that he can finally tell his dad he found a true friend.
Volume 4
The beach episode. The MC, Bro, Cow, Glasses, FMC, and the MC's little sister go to Bro's father's mansion in Okinawa for summer vacation. Before leaving, the MC remembers another heroine who transferred at the start of the second semester in his past life: Hiromi. Hiromi was relentless, actively isolating and tormenting the MC; if anyone tried to befriend or speak to him, she would attack them. Apparently, the old POS gang met her in Okinawa during summer vacation, though details were kept vague as everyone avoided discussing that trip.
The MC asks around if anyone knows Hiromi. No one does except Glasses, who has an odd reaction. Once in Okinawa, the MC meets Hiromi at the beach, where she asks him to fake-date her for a couple of days to beat her sister. It is revealed that Hiromi has a twin sister, Yuki, whom the MC never met.
Glasses asks to speak with the MC alone. Later that night, they both reveal their suspicions that the other is a reincarnator. Glasses suspected it when the MC started asking about Hiromi; the MC suspected it when Glasses mentioned Shohei Ohtani being a Dodger instead of an Angel (which shouldn't happen for another year). Glasses sincerely apologizes to the MC, promising to do anything to atone for her past sins. The MC asks her to stay with him, says he has forgiven her, and deduces that she also committed suicide in the previous life. (From this point on, Glasses becomes quite aggressive with sexual innuendos toward the MC, offering to be his lover, mistress, or "convenient woman").
It is revealed that Yuki will die in a couple of days. Glasses doesn't know the cause of death, but her death in the original timeline was the reason no one talked about the Okinawa trip. The gang sets up Bro and Hiromi as a fake couple to fool Yuki so Hiromi can get her "win."
Five years prior, Hiromi and POS met; she fell for him, and they made a promise to date if neither had feelings for anyone else (a promise POS never intended to keep, as he was obsessed with making FMC his heroine). Hiromi suffers from a massive inferiority complex toward Yuki, who excels at everything. Yuki sees through the gang's plot but plays along so she and her sister can reconcile.
Things seem resolved until the MC realizes at the last minute that the person he knew as "Hiromi" in his past life was actually Yuki—the real Hiromi was the one who died. Hiromi died searching for a legendary beach flower that grants a wish if picked on a specific date. The MC realizes the switch happened on that exact day during a violent storm. The MC rushes out to save Hiromi, and Bro joins him without hesitation. They find her just in time and save her from a wave—the exact way she died in the original timeline.
Glasses and Yuki arrive, and the full truth comes out: Hiromi wanted to beat her sister, but her true motive was to mend Yuki's relationship with their parents. Yuki was heavily doted on while Hiromi was ignored, making Yuki a major sistercon who resented their parents for hurting Hiromi. When Hiromi learned POS liked someone else, she sought the flower to get a boyfriend, beat her sister at something, fix her family, and help Yuki become independent. When Hiromi drowned, Yuki found only her phone and sandals on the beach. There, she met POS, who revealed everything. (POS had met Hiromi in Okinawa, despised her, but preferred Yuki—so he engineered events to get Hiromi killed and claim Yuki for his harem). Mad with grief, Yuki took Hiromi's identity, deciding to love POS as Hiromi did before "joining her sister," becoming the relentless force at POS's side in the past life.
With everything cleared up, the MC cheers them both up by endlessly flattering Hiromi and roasting Yuki. Bro joins in, delivering heavy blows to Yuki's ego. Furious, Yuki becomes obsessed with Tsukiyama, determined to prove him wrong. Hiromi joins the "losing heroine" group (hinting she likes the MC, though she won't challenge FMC, agreeing with Glasses to be a "convenient woman").
The volume ends with both twins transferring to the MC's hometown and tricking POS into revealing his hand. Yuki turns out to be a massive man-hater who despises POS, while Hiromi rejects POS, stating she already likes someone else. POS is left fuming that a "secondary heroine" turned him down, muttering that he only has one useful puppet left.
