OK, I managed to make a lot of progress. The only content I'm missing is the sex scenes with Riche, and the fight against the tentacle boss. For the latter, I remember reading in this thread that after getting the true end, you can ask Angelica for the key to the ruins—I assume that's where it is?
For Riche, however, IDK what to do. I have the quest you get from meeting her while she's fishing, which says "She'd be really happy if I gave her katsuobushi or something," but I can't see a recipe for that, or anything resembling it. Moreover, some days the conversation fairy will tell me that she's in the western forest, but I can never find her. She says it's during the night, which I've gathered from other quests is usually from 8 p.m. to 12 a.m. (as opposed to "midnight", which is from 12 a.m.), but at this time Riche is still in her house. She does disappear from her house come 12 a.m., but then the conversation fairy reverts to saying there's nothing special, and I can't find Riche in the woods, so is this a bug or what? Also, I don't know if this is another bug, but the Riche item quests seemed strange. Like, I would craft and item and give it to her fairy, but she wouldn't acknowledge it (I even tried talking to her at different times of the day). Just to make sure, I would craft multiple of the same item and deliver them once in a while, and then like a week later the quest would complete. This is a problem because for her last order (the amulet of resurrection), I'm not sure if the game thinks it's complete yet or not (it's "cleared" in the journal, but Riche hasn't said anything confirming this so far).
As an aside, the journal entries about "Fairies' bodies being too small" and "Angelica being mad at Lillia for having a bigger chest than her" are still incomplete, and I've no clue what I'm supposed to do.
Edit: Riche is indeed in the western forest from 8 p.m. to 12 a.m. despite simultaneously being in her house at that time, so I guess that's one thing I can cross off.
Edit 2: I managed to complete the "Angelica being mad at Lillia's because of her chest" quest; you need to get the tentacle in front of the ruins, have sex with her, and talk to her in the morning.