It starts off with a landlady using a stick to poke about a bag of garbage, which suddenly spills open to reveal a mutilated corpse with nails sticking through its right hand. Although unclear in the anime, TIPS from the game make it likely that the corpse in question is Mamiya Rina, who is not really referenced in this arc.
The scene changes to the Maebara residence, where Keiichi’s mother explains that the mentor of Keiichi’s dad has collapsed, so both of his parents are going to Tokyo for a few days to help out. A half-awake Keiichi mutters a reply, and time forwards to school. Satoko suggests he try cooking his meals himself, and the others in the group all agree. At home, Keiichi attempts to prepare a meal and succeeds in creating a fire which reach so high that it begins to burn the kitchen ceiling. Luckily, Satoko and Rika enter just in time to stop the house from burning down. After cleaning up Keiichi’s mess, Satoko begins to prepare dinner for the three of them. Out of Satoko’s hearing, Rika tells Keiichi that “this is the first time in a while that it looks like she is enjoying herself.” She proceeds to inform Keiichi of Satoko’s “nii-nii” (a pet name of sorts derived from the character “nii”, or “elder brother”), Satoshi. While they are eating, Satoko tells Keiichi that Satoshi ran away some time ago, and that she believes he will return unexpectedly one day. Keiichi continues to praise Satoko for her cooking, but when she asks Rika for her thoughts Rika compliments the canned sardines instead.
Keiichi sees the two off later that night, but Rika stays behind to tell him that he has earned “full marks” for the day, and asks him to play with Satoko more often so that she will continue to stay happy and hopeful for the return of her “nii-nii”.
The next day, Keiichi’s parents return and his mother tells him he has a phone call, from Satoko. She tells him that it has to with club activities and it is urgent that he come as soon as he can. Keiichi, fearing someone is hurt, rushes into the baseball field on his bike holding a golf club. As everyone looks on (much to the chagrin of Keiichi) Satoko slowly approaches Keiichi and asks why he brought a golf club. After a transition, Keiichi explains that it was merely a game between the Hinamizawa Fighters and the Okinomiya Titans. Keiichi performs terribly in the game, while Satoko is able to win the game 13 to 12.
After the game, Keiichi meets Irie Kyousuke, the baseball team’s manager and owner of the Irie Clinic in Hinamizawa. Irie openly admits to loving Satoko, and wants to marry her once she becomes older. He laughs at shock on Keiichi’s face, and tells him that Satoshi at one time was a top player of the baseball team. Whereas Satoko said her brother ran away, Irie says he “transferred” away three years ago (much like the responses Keiichi was given in Onikakushi-hen). The doctor explains that their parents “fell off a viewing platform at their holiday destination”. This is why Satoko lives with Rika (Rika’s parents also died). Irie says he has considered adopting Satoko, and Keiichi asks him what he would do if he did. Before Irie can answer, Shion appears behind the two guys (in this arc, Keiichi appears to have been told who she is) and replies “I’d make her call me ‘master’, and then I’d train her to become a maid at my beck and call.” Before that is carried any further, Shion explains that she is a “phantom” manager, which was why she was absent from the game.
That afternoon, Keiichi is washing off plates from the after-game celebrating while Shion compliments him on his “stellar” performance. Keiichi denies it, and instead points to Satoko’s home run as “stellar”. Shion thinks Satoko took in her reflexes from Satoshi, and eventually Keiichi states how he “transferred” away after the death of his parents. Shion reacts violently, demanding he tell her who said Satoshi “transferred”. Keiichi asks why she would ask that, and Shion composes herself. She begs him not to say that again, when he never even knew Satoshi. Shion leaves before Keiichi can inquire any further.
On the way back home, Keiichi asks Rena and Mion about Satoshi. Just like in Onikakushi-hen, Rena replies that he transferred. The two girls are surprised that Keiichi seems to know that Satoshi ran away, but they have no idea where he disappeared to. Mion tells Keiichi that although the villagers and police searched, Satoshi was never found. She remembers a detective report that stated Satoshi had a steady income, but withdrew it all on the day he vanished. A person was also spotted at Nagoya Station that allegedly looked like Satoshi. Rena believes it is all lies, and in the ominous voice that wasn’t present in Watanagashi-hen, she knows it to be Oyashiro-sama’s curse. She tells the others that before his disappearance, Satoshi told her he was being watched, that he was being followed, that something watched him while he slept. Mion tries to stop Rena, but Rena continues to say that deep inside himself, Satoshi wanted to leave Hinamizawa. According to her, Oyashiro-sama could not forgive such insubordination. Rena tells Keiichi she had apologized for feeling that way [and was forgiven], but Satoshi did not. Thus he was cursed. As Rena’s demented rant begins to make her shake back and forth, Mion strikes her across the face, again telling her to cut it out. Mion changes the subject, and Rena leaves peacefully. Mion doesn’t want Keiichi to worry about what happened.
As per Mion, Satoshi’s parents had been the leaders of those in favor of the dam, much to the spite of the three great families and most villagers. Mion confirms it when Keiichi says that Satoshi’s disappearance, like his parents’ death, were listed as examples of Oyashiro-sama’s curse. She says that all this is unpleasant to Satoko, so when they reply that Satoshi transferred, they due so out of respect for Satoko. Before Keiichi leaves, Mion requests that he not discuss Satoshi around Rena either. When asked why, Mion points out how she had just acted was an example of the strictness Rena applies to herself whenever the topic is brought up. Keiichi wonders what her reason for doing so is, and Mion says that according to Rena, the girl had a run-in with the curse itself. Keiichi accedes, and decides not to speak of Satoshi again.