The episode opens with a sunrise and the voice of Tomitake Jirō protesting that Takano Miyo would never execute the "Emergency Manual" on purpose. The child voice of Rika reminds him that Irie has said the same thing, but since Takano knows her research will end in three years, Rika feels she will become desperate. The scene resolves to the outside of the Furude Temple with Rika addressing Jirō and Irie. Irie agrees and notes that Takano's appeal failed. Rika explains that if the "Emergency Manual" is executed, "someone is going to be held responsible," and someone is trying to take down a rival. She tells Jirō that the Yamainu will murder him. Jirō laughs it off, but Ōishi Kuraudo appears to tell him to take Rika's predictions seriously since she predicted the chain of murders five years prior. He then tells Rika he has brought someone who wishes to meet her. Akasaka Mamoru appears and suggests that Rika will not tell him to go back to Tokyo again. In tears, Rika hugs him and repeats his name. Jirō and Irie observe this with surprise. Akasaka explains to them who he is. He then states--while Rika still cries--that five years ago she saved the life of his wife. This is an important detail in that in some previous lives, five years prior to this time, his pregnant wife slips, falls, and dies. Rika had warned him to return to Tokyo, and if he does, he succeeds in preventing this accident. He vows to her it is his time to repay her.
The scene refocuses on the Sun to suggest a passage of time. Akasaka explains the "Alphabet Project" which consists of a source of illicit money his team investigated for years. Each year, it transferred a great sum of money to the Irie Institution. Irie protests that "Tokyo" aside, his group is not doing anything they would need to hide. He claims they merely seek a cure for Hinamizawa Syndrome. Jirō asks Rika how she learned all of this information. She explains that she is the heir to the Furude Shrine and has Oyashiro-sama on her side, then looks away embarrassed. Jirō accepts that answer "for now" to Rika's surprise: "This is the first time you've ever taken what I said seriously." Since they will have to wait for Jirō to find evidence, Rika asks Ōishi if he could find a reason to take Takano into custody. Ōishi muses he may lose his retirement allowance, but will do it if it is necessary. Irie reminds him that the Yamainu probably have spies in the Okinomiya Police Station. Akasaka suggests that Ōishi withdraw from the case given the risk to his retirement. Jirō agrees. Ōishi tries to laugh off being "lectured by youngsters." He muses that he planned, after retirement, to make a vegetable garden and take up ballroom dancing in Hokkaido. However, he feels his biggest risk is to lose the ability to search for those who killed the manager of the dam construction project. Rika replies that the true culprit behind all of the murders is not the Sonozaki family.
The scene shifts to the Sonozaki home. A surprised Keiichi asks, "You weren't talking about manga?!" Satoko confesses that when Rika revealed the truth the previous night, "we were shocked as well." Mion affirms that they knew she was serious. Rena pledges her support while Keiichi states that if it is a "bad joke" he will be very angry. Mion reaffirms the situation is not a "game," and Rika apologizes to them all for involving them. Hanyū sadly reports that Rika has been constantly apologizing. A smiling Satoko breaks the tension by suggesting it would have been ruder for Rika to have kept her situation a secret. Keiichi picks up on this and proclaims that everyone must be secretly excited: Satoko has been waiting for an excuse to use her traps without holding back. Rena can "pull off some dangerous stunts," and she reminds him that he can crush fate no matter how hopeless it may be. Hanyū suggests that if he is a "red, burning flame," then Rena is a "blue, gentle flame." Keiichi then turns to Hanyū and notes that although she is a recent transfer, she already understands them all. A chibi Hanyū "au-aus" in response to the flattery. Keiichi proclaims that it is their festival, and they will set off spectacular fireworks. Listening to this, Rika says in her adult voice to Hanyū that she is happy. She never imagined everyone would believe her. Hanyū responds that everyone is growing. There are quick flashbacks to Keiichi bludgeoning Mion and Rena, Keiichi being stabbed by Shion, Shion's insanity and Keiichi's reaction to Rena, and finally to all of them pledging to help Rena, then all pledging to work together from the end of Minagoroshi-hen. Over these flashbacks, Hanyū explains that even if they do not clearly remember these past events all of the past events remain somewhere in their minds. Rika agrees that perhaps all of their experiences were not in vain.
The scene shifts to the Irie Clinic. Inside, Irie asks Takano if she intends to continue the research after the Irie Institution closes. She asks him why he asks, and he nervously responds that he is uncertain of his future position. She admits that private research will prove difficult as it was with her "grandfather." Irie asks about her association with Takano Hifumi. She admits he adopted her and that she seeks to complete his research and have it recognized. She further admits that once the Institute and its research is shut down, then the work will become "shrouded in darkness" and her wish will not be fulfilled. She then laughs.
The scene then shifts to the Sonozaki home and Mion reviewing the plan: Rika, Satoko, and Hanyū will hide in her home. Akasaka will stay in the house they had lived in to give the impression they still live there. The scene shifts to Akasaka in their home looking out of the window until the phone rings. The scene returns to the Sonozaki home and Keiichi asks if Akasaka will be safe there. Hanyū happily says that he is incredibly dependable. Mion notes that he is a safe-guard and the most important role is Jirō's as the scene shifts to a hotel in Okinomiya. It is his job to find evidence. As Rika explains this, the scene shifts to Jirō talking on a hotel phone as he "doodles" the connection between "Tokyo," "Takano," and "Okonogi" with the numbers "03-671-2" underneath on a hotel stationary pad. If he can find the evidence he can call in a stronger special forces unit--"Banken" or "watchdogs"--to take care of the Yamainu --"Wild dogs"--literally "mountain dog." Keiichi wonders if they can unbalance their enemy. Mion reminds everyone of the theory that if Rika dies, within 48 hours the Hinamizawa Syndrome will effect everyone. Rena notes that if they cannot kill Rika, they cannot institute the Emergency Manual. Upon hearing this, Satoko leaps up and claims she knows the enemy's weakness and Keiichi exclaims that he understand it as well: Rika just has to die. As Satoko and Keiichi chortle in triumph, and the rest watch in confusion, the scene fades into the commercial break.
After the break, Irie knocks on the door of Satoko and Rika's home loudly asking for Satoko, Rika, and Hanyū and announcing himself as their "Master"--ご主人様--goshūjin-sama--"your husband"--arriving for their checkup. Akasaka answers, and Irie whispers that he is alone. Akasaka responds that there is evidence the home is being watched. This further convinces Irie that Rika's claims are true. He brings Akasaka provisions and the two workout a system of signals should an emergency occur since the phone is probably tapped. If Irie lets the phone ring one minute then hangs up, it means danger and Akasaka should escape. If it rings longer that means that Irie cannot contact him and Akasaka should immediately go to the Sonozaki home.
The scene shifts to Sonozaki's home with Ōishi expressing surprise that he should pretend Rika is dead. If they pretend Rika has been dead for 48 hours, the failure of the Hinamizawa Syndrome to affect the people will undermine the excuse to proceed with the massacre. Ōishi agrees this will throw Takano's people into a panic. Hanyū explains that they need his assistance. Ōishi muses he must prepare himself for the consequences. Hanyū replies that he does not have to agree to the plan if he does not want to: "We don't mean to use you as a steppingstone towards victory." Ōishi laughs and states that if a "youngster" tells him that he cannot refuse. He continues that he cannot give them an answer immediately since it will involve his colleagues. Hanyū excitedly explains that he should not worry because if he loses his retirement, Mion will make arrangements for him. Mion startles and Rika lets out a happy "Miiiii! It's the least you can do" for Ōishi's assistance. Hanyū and Rika agree
with a "neee!" and a hysterical chibi Mion reacts to the sudden financial obligation. Ōishi admits he has no chance against them. The scene shifts to Jirō on the phone in his hotel room. The voice tells him that there are "some obscured sections in the Irie Institution," which the "Investigation Bureau" is now investigating. The voice also mentions the close relationship between the Late Koizumi and Takano, which probably explains the efforts to establish the Irie Institute. The voice notes that Takano Miyo may have received "one billion yen" [= ~$4,545,455 in 1981 or $14,017,128.34 in 2016] which would be more than enough to bribe the Yamainu. Jirō is shocked by this amount. Viewers should remember that he is responsible for overseeing the finances of the Irie Institute. The voice admits that Takano Miyo may very well be involved in some sort of conspiracy.
The scene shifts to the Furude Temple and the preparations for the coming Watanagashi Festival. We hear the voice of an old woman stating she heard that Rika has been ill. The scene focuses on Irie being questioned by three older women who also note that Satoko has also been staying at home. Irie seems surprised at their concern over Satoko. He even asks about their concern given how her family was hated by the village. One of the women admits that perhaps the family was, while another states she does not want to see any child suffer. At that point Sonozaki Oryō arrives with Kimiyoshi Kiichirō. She asks him if Rika will be well enough to perform the ritual dance. She playfully admonishes him to "patch her up" before the Watanagashi Festival, but then she adds that she does not merely speak for Rika but "that Hanyū girl as well." This underscores that Hanyū can now be seen by people with whom she has not interacted. Oryō also adds, "and Satoko, too." Irie and the old women seem surprised, but Kimiyoshi explains he just talked with Oryō and she agrees they should not cling to the past "curses, grudges, and whatnot." "The dam war is long over," concedes Oryō, "if a kid of the village catches a cold, it's the job of the elderly to worry about them." A happy Irie proclaims that Satoko will be happy to hear that.
The scene then shifts to the late day and Ōishi visiting a grave of the manager of the dam construction project. He asks if the deceased laughs since it turns out that the Sonozaki family had nothing to do with his death. He continues that he has come every year promising to arrest Oryō. Now, he is "about to cross a dangerous bridge." While the result may not balance the risk, he might learn the truth behind the murders. He is surprised by Shion and her mother Sonozaki Akane bearing offerings. Akane states it is the first time they have met at the grave. Ōishi notices that she carries the hydrangea that he has found placed at the grave every year. Shion states that she carries ohagi made by her grandmother, Oryō. Surprised, Ōishi asks why, since the deceased had such a bad relationship with the Sonozaki family, they would do this. Akane explains that after a kendo or rugby match, there are no allies or foes. Children will take over Hinamizawa, and the adults must end the dam war for their sake. Ōishi agrees that there are "great youngsters" living in Hinamizawa, and he has made his resolution. Addressing the deceased, he declares himself a detective who will do his part in "Mion-san and Keiichi-san's festival."
The end titles cease with the Pathologist slamming his beer bottle on the table in the traditional restaurant announcing he will join Ōishi's plan. Ōishi wonders how he can decide so quickly only to have his subordinate announce that he will join as well.