Same disclaimers, etc. etc. don't read if you haven't finished Higurashi as it will sound crazy and spoil you a hell of a lot.
Chapter III: Tatarigoroshi [Killed by the Curse]
Q: This chapter seemed to be trying really hard to convince the reader that something supernatural was going on.
A: By the time the average person reaches this chapter, they likely have some theory of what's really going on in the story. This chapter is meant to try to poke you onto a certain route. But if you're paying attention and are able to separate the truths from the disinformation, it's one of the most informative 'question' arcs there is.
Q: So if Satoshi is dead in a canal at the opening of this chapter, then how can he still be alive in the basement of the medical clinic?
A: This is perhaps the most misdirecting 'clue' there is in the entire anime. Go back and watch the first episode. Yes, the corpse that is dug up has blonde hair, but freeze the episode on the part where they show the intestines. Do you notice that there's a red tattoo-star on the hip of the dead body? Who has a red star tattooed on her hip...?
Yes, the dead body at the beginning of this chapter is NOT Satoshi, but Mamiya Rina, the home wrecker who targets Rena's dad in Tsumiboroshi-hen. We know from Minagoroshi-hen that Rina being killed by the Sonozakis means Satoko's uncle returns home, so that's what's being foreshadowed here.
Q: Why does Satoko call Satoshi 'Nii Nii'?
A: 'Nii' (as in 'nii-san' and such) means brother. But besides this, "nii nii" is also the name for another species of cicada, much like the 'higurashi' in the title. So if Keiichi is a higurashi cicada, Satoshi is a 'nii nii' cicada.
Q: Why is Oishi such a jerk in this chapter?
A: I think Oishi is presented in such a dark light in this chapter to give a clue as to Onikakushi-hen, ie that Oishi is not generally a force for good who has the kids best interests in mind, but someone with his own agenda. Nevertheless, when they first meet Keiichi refuses to be helpful and then later when they meet again in the rain Oishi is 99% sure Keiichi murdered Satoko's uncle (which, to be fair, he had), so it makes sense for Oishi to be less kind this time around.
Q: Why does Shion get so upset when Keiichi asks if Satoshi 'transferred'?
A: We know from TIPS and from Meakashi-hen that Shion was really in love with Satoshi and suspects her own family was behind his disappearance, and we also know that Mion and most hinamizawa people just say Satoshi 'transferred' when he's brought up. It's pretty clear why Shion gets so upset.
Q: If Satoshi didn't leave town, then what is the story behind someone seeing someone 'like Satoshi' on a train?
A: There is the possibility that Satoshi started to leave, but then changed his mind and went to buy the bear with Dr. Irie, but more likely the real answer is something that just hasn't been explained. I don't think there's a relevant TIP or anything else in the original games that explains this either...
Q: Takano Miyo asks Keiichi if he's remembered her yet this time around. Is she possibly remembering all of the previous Hinamizawas, like Rika...?
A: No. Takano Miyo is just creepy and was commenting she'd seen him numerous times.
Q: Why does Takano tell Keiichi what she does about the Sonozakis?
A: Because Takano likes stirring up shit with the Hinamizawa kids and Keiichi is really presenting himself as an easy target for paranoia this chapter. In the games, Takano makes Keiichi swear never to reveal she was the person who told him the information, so much like Rena's scrap books and what Takano tells Shion, this is just another case of Takano trying to spread paranoia on her own.
Q: Why does Mion claim her family never kills people? The Sonozakis obviously killed Rina.
A: Rina was killed because she was trying to steal a hell of a lot of money from them; she was not killed because she was set as a 'target' for the Watanagashi curse, which is probably what Mion meant.
Q: Is it Mion or Shion Keiichi is talking with on the phone when he asks her to take care of Satoko at the festival?
A: This is another thing that is sorta vague. You could make the case it's Shion because she seems to know that Satoshi killed his aunt, but it could also be Mion because we know the Sonozakis created a false 'drug addict' scapegoat. We'll probably never know for sure.
Q: Okay, the meeting with Takano giving Keiichi a drive home was really creepy.
A: Wasn't it? Their meeting is perhaps the biggest up-front clue Higurashi provides in the question chapters. Here's a list of what is revealed:
1. Takano is driving home from Watanagashi, she is alone.
2. The trunk of her car is full, but she won't say of what. (We know from Minagoroshi-hen that an unconscious Tomitake is in the trunk.)
3. Takano also has Tomitake's bicycle with her, but claims it's hers. (It isn't.)
4. After dropping Keiichi off, she tells him: "We didn't meet tonight." When he asks her why that might be better for both of them, Takano brushes him off with a dark: "Oh, figure it out yourself, boy."
Q: How did Takano know Keiichi was out killing Satoko's uncle?
A: She didn't know exactly WHO Keiichi was out killing, exactly. But really, Keiichi may as well have been wearing a big sign that says: "FIRST TIME MURDERER! :D" Takano finds Keiichi walking around in the pouring rain, no umbrella, with only a bike and a big ass shovel, and then the reasons Keiichi gives for being out are contradictory. Furthermore Takano knows about Hinamizawa syndrome, and given the paranoia she was feeding him earlier in the chapter, it's not a big jump for her to assume he was out doing some killing.
Q: Why does everyone act like Keiichi was at the festival? Was he really cloned?
A: No, the whole 'doppleganger' and 'clone' story is just disinformation. What they were really doing was lying to create an alibi for Keiichi like Shion does with Satoshi. This is why Rena acts upset when Keiichi leaves to go to the doctor's office: they were getting ready to tell him what was going on. Unfortunately Keiichi let his imagination run away with him and he doesn't talk to any of the Hinamizawa kids (except for Satoko) for the rest of the chapter.
Q: Did Dr. Irie not believe Keiichi's confession? Why did he try to drug him?
A: Dr. Irie likely DID believe Keiichi's story, but at the same time was NOT planning to turn him into the police, but keep him at the clinic to treat his Hinamizawa syndrome. We've seen in Matsuribayashi-hen that Irie did the same thing with Satoshi: he got Satoshi restrained and then started trying to treat him. Ironically, Keiichi running away from the clinic was quite possibly the worst thing that could've happened to him.
Q: Okay, who moved Satoko's uncle's dead body?
A: Chalk it up to the Sonozaki family's doing. It's pretty much common knowledge after the festival that Keiichi was killing Satoko's uncle, and his skills at burying a dead body are somewhat lacking. Much like how the Sonozaki's move the dead bodies of Rina and Teppei in Tsumiboroshi-hen after Rena kills them, we can assume they do the same thing with Teppei's body in this chapter.
Q: If Keiichi really killed Satoko's uncle, why does Satoko still torture herself like he's still alive?
A: Satoko is a level 3 Hinamizawa syndrome case. She's only as calm as she is usually because of the medicine she receives from Dr. Irie's clinic. Satoko's uncle coming back means her treatments stop, which means her syndrome gets really bad, which means she puts together a bleak view of the world around where her uncle is still around. And Keiichi is paranoid enough he's fooled by it.
Q: So, the Yamainu poisoned Dr. Irie?
A: Yep. It's pretty common for Dr. Irie to die, this is just the first time we see it happen.
Q: Okay, then why is Oishi killed? Usually he lives!
A: We know from how Oishi and his partner Kumagai die in Minagoroshi-hen that the police officers getting killed off is actually pretty random. In this case, Oishi isn't only investigating the Takano/Tomitake murders, but also Teppei's murder and stalking Maebara Keiichi as the prime subject. In other words: Oishi's doing a lot of legwork in this chapter. More getting out means more chance to meet the Yamainu at a bad time, which results in him getting sniped.
Q: What happened to Satoko after she shoved Keiichi off the bridge?
A: She most likely went insane, and either tore her throat out or got killed by the Yamainu. Poor Satoko. :(
Q: Is there anything else to note that was included in the games that didn't show up in the anime?
A: Yes. There's a scene in the Hinamizawa school, before Keiichi kills Teppei, where Keiichi is spaced out and not paying attention, and Rena looks in his eyes and says: "Wha-- what cold looking eyes! You're... Maebara Keiichi-kun, right?" Which is another disinformation attempt to make the reader think the answer is "the kids get possessed by evil."
There's also a long list of the fates of all the Hinamizawa residents that die in the sterilization of Hinamizawa. Shion is mentioned as another survivor, but she dies from the Yamainu 'nurses' pretty quickly.
Q: What happened to Keiichi after he was 'rescued'?
A: He got put in a hospital as the sole survivor. There is a long drawn out scene in the manga and games where Keiichi gives an interview with a newspaper reporter about the incident. It's revealed that the place Keiichi woke up from after he fell was supposedly the source of the gas leak, which makes the reporter question Keiichi's honesty. In the end, Keiichi gets fed up and tells the reporter that he wasn't sure if he could really predict people's deaths like what happened to Takano/Irie/Oishi, but he'll try it again. He tells the reporter he'll die of drowning, yells that he's the human-messenger of Oyashiro-sama, and then dies of 'heart troubles' about a day later. (It is also revealed the reporter does die of drowning eventually.)
Q: Why do the Yamainu just leave Rika's dead body at the shrine for anyone to find?
A: To prelude the sterilization of Hinamizawa. There's an old rumor (revealed in the TIPS of the original game) that if the villagers do not properly honor Oyashiro-sama, or if they anger him, Oyashiro-sama will engulf Hinamizawa in a horrible killing-fog which will kill everyone. Leaving Rika out means someone finds her corpse the early-morning of Hinamizawa's last day, which means the entire village starts panicking because of Rika's death and the old legends, and makes the actual sterilization of the village just that more chilling.
Q: This chapter was depressing. :(
A: It's actually pretty tame, compared to some of the other ones.