1. If you're referring to Tanjirou's statement at the start of Ch 125 (last week's), it's that they risk Hantengu fleeing like Akaza did, when he fled before the sun gets him killed
When I was browsing the Shonen Jump Baidu board, I got spoiled on the ending of this week's chapter. At first I didn't believe it, then I got ticked that I got spoiled.
That being said, the events that actually led up to it was compelling. The Kamado siblings are so likable.
I think cause she’s a special case that shes actually half human and half demon so in the sun she turns back to human and at night she turns into a demon. They jus never knew cause they never took the chance to test it.
2. I'll trust that Gotouge-sensei knows what she's doing. After all, this entire time the exact nature of Nezuko's state of being has been shrouded in mystery, with only in-universe speculation to go on.
- Considerable strength even without consuming human flesh or blood
- Has regeneration that's on par with the Upper Moons
- The fire from her Blood Demon Art has the same purification effects as sunlight
Going over the internet, there are two major camps of thought as to why sunlight, while very evidently still burns her, didn't kill her:
(1) Given how all demons are effectively infected humans, that pretty much makes all of them half-humans, so I rule out that as an explanation.
However, if the Demonification in this story is in fact an infection of sorts meant to give pseudo-immortality, and consuming human cells propagates it, then what actually happens if Demons don't actually consume any?
Could it be that because Nezuko hadn't eaten any humans at all, there's a limit to how much of Muzan's cells are actually in her body? And while the sunlight burns these away, because the Demonification didn't get to propagate much, her body still mainly consists of cellular material that sunlight doesn't affect?
This is a shaky theory though. After all, Nezuko still has fangs, claws and pink eyes that show her demonic traits are still there.
(2) On 4chan, somebody pointed this out from Chapter 39, when Tanjirou's life flashed before his eyes
In one of the panels here, you can see a Spider Lily. And it's not shaded like it's the usual red
Muzan has been looking for this Blue Spider Lily, a plant of properties still unrevealed to us readers. Our current speculation is that it's something used to strengthen demons, possibly to overcome their weakness to the sun.
But, if that speculation is on the right track, and if the flower shown in Tanjirou's flashback is in fact the Blue Spider Lily, then that would mean it could've been found in the Kamado household's mountain.
And what if something led to Nezuko consuming it before she got struck when Muzan attacked? Is that why she has been so special?
As to my current thoughts, I have a feeling that things aren't as easy as it looks.
Like, my stance is that Nezuko won't always have the best of both worlds. My current idea is also that more human traits will surface at daytime, and more demon traits will surface at night, including the hunger to feed on humans.
This way, Tanjirou's goal of curing Nezuko still holds value, while not diminishing her battle prowess and still gives her more chances to shine as a character by having chances to talk.
And with talking, we may finally get her testimony on what transpired on the night of tragedy.
First Genya's unique temporary demonification and now Nezuko's unique nature. Gotouge-sensei has to be planning something putting these reveals so close to each other.
Right before this arc entered battle phase, Tanjirou wondered if they should see Tamayo for an update. Now I really hope this is the next arc, and would be cool to see her examine Genya.
For such a prospect, I would like party members to include Nezuko, Genya, Zenitsu and Inosuke. Tanjirou may be optional, rests at Butterfly Inn.