Since I’m just now getting to chapter four, I can write up my thoughts as I go:
Interesting to see there’s a 描き下ろし so early on. With レンタルおにいちゃん, such chapters were added throughout the series to help build up to the ending. For 幸色のワンルーム, considering volume 9 just came out earlier this year, I’m wondering if these 描き下ろし will better tie in upcoming (near) events, or if they’ll be more like OVA in an anime, adding fun material without progressing the plot.
Page 86: A request made while completely unaware of their situation. Sounds like a teenager.
Page 87, second-to-last panel: His expression makes me think of a person who went out and got a pet, then found out they have to actually spend time with it.
Page 88: It’s been a year and a half since I did the lesson for it on WaniKani, but I finally get to see 条件 in the wild! Since I burned it about four and a half months ago, I did have to think for a moment of what it meant. Context to the rescue! (Otherwise I might have guessed “treaty”.)
Page 89: I feel like she keeps jumping back and forth between being cautiously on guard and being peppy.
(At this point, I’ve had the feeling like maybe he’s testing him, to see how he’ll react to her whims.)
Page 92: Considering how we were taught about は and が in my high school Japanese class back in the stone age, I always enjoy seeing sentences that utilize both. Since learning the difference (thanks Cure Dolly!), such sentences, utilizing both, feel satisfying to read. (Our textbook taught us that は and が are basically the same, and even Japanese people don’t really know the difference, so we should just always use は.)
Also page 92: Here’s where the causitive throws me off. Is she asking “will you make me (do it)” or “will you let me (do it)” (as in, not try to stop her)?
Page 93, final panel: I’d hate to be the person tasked with translating this into English. While one can assume whose thinking by who’s shown in the same panel, the 僕 makes it quite clear in a way that you can’t really replicate in English…
Page 94: I always thought うそをつく was 嘘を付く, but doing a web search comparison, apparently 嘘を吐く is used three times as much. And 嘘をつく is used five times as much as the two kanji variants combined.
Often a web search for two kanji uses with 違い will yield results telling in which situation/scenario to use which kanji, but I don’t see anything like that for these two. Instead, I found someone saying 付く is incorrect kanji/word usage. The reason: 吐く is transitive, and 付く is intransitive. That makes sense.
It looks like 嘘を付ける and 嘘をつける see a lot of mileage.
Page 96: Ah, this gives me a visual image to add to my Anki card for 変装.
Screenshot of Anki card (back).
That visual aide will help me remember the word better (hopefully).
It doesn’t match my card’s sample sentence, but my cards not sourced from immersion typically have a sentence (front of card) and image (back of card) that don’t match up (just both relate to the vocabulary word).
Also page 96: It sounds like our お兄さん is probably at least 23, maybe closer to 25.
And again, page 96: Where’d she get the glasses? Do they have plain glass lenses? (I don’t wear glasses, but one time when someone let me try theirs out, it made me super dizzy in a few seconds, and my eyes were sore/strained for some minutes after.)
Page 101: If you wanted to indirectly let people know you’ve been kidnapped and this is your first time outside in a while, here’s what you would say.
Page 106: I think I just bonded with our kidnapper a bit. When I’m asked a question along the lines of “is X Y?” and X isn’t Y, but it’s close enough to not warrant an explanation as to how they differ, I tend to reply with, “Something like that.” And here we have 「そんなところです」 which sounds fairly close!
Page 108: Someone’s a quick and clever thinker.
Page 110: Makes me think of when I see a person in the grocery store where they’ve opened box of snacks or bag of candy they intend to buy, and they are eating it as they walk through the store. Is it really that hard to wait until after actually paying for the item? (Our kidnappee can probably be excused, at least this once. I’m counting on our kidnapper to ensure she doesn’t grow up to be one of those adults, snacking while grocery shopping!)
Edit: Also, parents who open a box of snacks for their kid in the cart to snack on. That’s just teaching a whole new generation to eat food they haven’t paid for yet! (Then again, come to think of it, technically that’s how restaurants work.)
Page 118: Ah, big cliffhanger!
Haven’t read chapter 5 yet but I’m really curious about the whole “I don’t know how shops work” part. I mean, she definitely went to school so it seems a bit unlikely to me that she never picked that up, even if she never went shopping herself. I’m hoping this is her being clever and trying to push お兄さん somehow.
I have a pretty mild prescription, but I tried some on once that had a strong prescription and I just couldn’t see at all. 
