1: This isn't the first time Ueno has lied about what one of her inventions is really for, and while the original explanation is very simple, her secondary explanation involving the + and - settings had one detail I couldn't determine the importance of. The wording used in the final bubble is 擬似的な介入, which reads like "pseudo intervention" (I changed intervention to entering/invasion because it sounds better imo). Does this mean you actually enter the other person's dream and then control it from within, or do you influence it in some way without being fully "inside" it? I wasn't sure what implications the "pseudo" had here, and it seemed awfully important.
Also, I wasn't too sure what 半覚醒状態 "half-awake" (or half-asleep) was doing in the second bubble there. Does a headset in the Plus mode not hypnotize you to the same level of sleep?
2: So, Ueno clearly has some method lined up to interfere with Tanaka's dream and make it about her, but unfortunately, she sees she is already present in Tanaka's dream. She reacts in a way that makes it obvious this introduces some wrench into her plan, even saying it's pointless to try right as she's putting the headset on. Is this existing Ueno the reason she ends up in her own dream instead? Did she know that was going to happen as she was putting her headset on? What made her change her mind and go to sleep anyway if her plan had already failed? And did the setting on her headset matter at this point?
3: We see the headset on Tanaka is clearly in Minus setting after he's fallen asleep. The last shot of the headset Ueno dons is a Plus on the earpiece, which is even drawn similarly to the one shown during the second explanation:
By all appearances, everything about this save for the Ueno in Tanaka's dream was how the plan was intended to unfold. So what is Yamashita going to speak up about right before Ueno falls asleep? What could she have noticed that Ueno didn't already know? She probably changed her mind because it would be fun to watch both of the other club members' dreams or anything simple like that, but why speak up in the first place?
This Yamashita part was the single most confusing thing from the whole chapter for me, and had me wondering if the twist was somehow that Ueno's headset mistakenly switched to Minus setting, but we don't see any proof of that in the end, so if that was the intended joke, why not draw it in? I couldn't determine if that was supposed to be implied or not.
4: Ueno talks about pushing buttons - an element of Tanaka's dream - upon arriving in the dream world. Does this mean she actually thought she'd made it to Tanaka's dream? Did she forget that the plan wasn't going to work because she's now in a dream? Was she dreaming that her plan had succeeded? That much makes sense, in a way.
And regardless of whether it was because of the existing dream Ueno or some problem with the headsets, we see Ueno's plan failed all the way through the end, because Tanaka's still got his pencils in the final shot of the monitors.
