It starts with Kumoko leaving the labyrinth and destroying the fort though she's still Ede Saine. Her soul attacks on "Mother" are discussed at length and Kumoko feels safe because Mother can't escape from the labyrinth and since she has Heresy Nullity, she can slowly chip away at Mother's soul and eventually win. There's even a scene from the Parallel Wills as they attack Mother's soul - set in a kind of spiritual/mental realm. All her Parallel Wills are focused on "Mother" and at some point contact between them is blocked somehow (probably Divine Dragon Barrier).

Mother specifically waited for Kumoko to leave the Labyrinth, then blasted a hole up through the labyrinth so she escape. She immediately then fires a long distance blast at Kumoko who had walked as far as a nearby forest. Kumoko just about manages to evade. She has to keep running while being bombarded while she prepares a long distance transfer (which takes some time to complete).

On a side note, it's clear to us now that Ariel is behind all these actions from the spiders. One thing is that Kumoko first started to notice the Kin Domination skill during her fight with Fire Dragon Rendo - probably referring to "116 - Spider vs Fire Dragon ④" when she has the thought: ...? Hate? Huh? Although I thought that the Earth Dragon is scary, I never really hated it. Huh? Where does this feeling come from?

Kumoko gets quite badly damaged by the time she finally manages to transfer to her current "my home" in the Labyrinth. But.... there's 5 Arch Taratekts waiting for her (as well as other spiders)! Kumoko manages to escape from them (after taking more damage) and runs towards the middle layer but runs into a Puppet Taratekt who slices her up with swords (it wields 6). Kumoko uses the Evil Eyes to slow down the puppet and Arches to buy herself some time. She's been surviving on 0 HP with Patience for quite some time and is a total mess.

Kumoko decides to take a risky gamble on levelling up and fires the Evil Eye of Destruction (the Corrosion attribute one) at the weakest Arch, which lets her level up. This recovers her body (though not her status completely) giving her enough time to do another long distance transfer deep into the middle layer after grabbing one of the Arches. She then evolves into Zana Horowa, gaining Immortality (and D appears like in the WN).

After the conversation with D, Kumoko leaves the labyrinth again and finds the sea/ocean. She tries to swim (similar to WN) but is too buoyant. Some sharks attack her but she kills them. The blood draws more sharks and the sea around her becomes red. There's a colour image from LN4 with Kumoko imaging her vs sharks as some kind of B-movie - this is that scene.

Anyway, around this time the connection between Kumoko and the Parallel Wills is restored and one comes to warn Kumoko to run away ASAP because there's someone even more dangerous than Mother involved. Unfortunately, it's too late and was actually a trap - Ariel deliberately allowed the communication so that she could locate Kumoko (via Kin Domination link through Mother). Ariel arrives so fast it's pretty much like she teleported. Of course, Kumoko can't understand what Ariel is saying at this point (not eaten Mother’s soul so doesn't understand the language) and Kumoko isn't able to run away (she was preparing teleport but didn't have time to complete it - not that it would have worked). Ariel splatters Kumoko with a mere swing of the arm. Game over...

The Parallel Wills feel that the main body was “killed” but the connection didn't die. They don't know why they didn't die (they don’t know about gaining Immortality) but decide that the main body must have done something so they keep on attacking Mother's soul.

Sometime later, Kumoko regains her consciousness. She's floating on the wide open sea. And, she has just her head! (LOL!!) She decides it's too dangerous to teleport anywhere (since Ariel might have prepared something) so just continues to float for many days like seaweed. After killing enough Water Drakes and a Water Dragon she recovers enough that her whole body is back (she doesn’t get full body recovery on level up anymore).

She then begins guerilla-style attacks on Mother and the spiders in the labyrinth while keeping a close eye on Ariel (who she marked with Wisdom). She kills all the Arch Taratekts and most/all of the Greaters. Her biggest worry is the Puppet Taratekts since they have better status values than her (except in magic). She's even more worried when it turns out there's 10 of them (though only some are in the labyrinth). She lures a bunch of them into a small chamber, seals the chamber with Earth Magic, then floods the chamber with sea water (she used her Item Box type feature from Space Magic). Naturally, the puppets can't swim and also float to the top. Kumoko took the Swim skill (despite the cost) which puts her in a better position and also she can't drown due to Immortality. She fires magic at them to weaken them at the same time and also to distract them - if they'd kept calm and ignored her they could probably have destroyed the walls but Kumoko used herself as bait to prevent this. So she basically drowned them! (Nasty plan Kumoko...)

Eventually she feels safe to go attack Mother - she'd seen through Wisdom that Mother's status values had dropped a lot, into the mid-thousands. Kumoko has way better status values at this stage, so teleports to Mother, who is at the bottom layer. However, it's a trap. Mother still has better skills - like God Weaving Thread and Divine Dragon Barrier. So Kumoko's normal situation has been reversed - despite her better status values she loses in skills and fell into a trap. Eg the ground is covered in sticky threads - Kumoko has to cut off her own legs to escape. The Divine Dragon Barrier weakens her best skills (magic) a lot. It's looking pretty hopeless but then the Parallel Wills return.

Since the Parallel Wills had been eating Mother's soul that allows them to bring Mother's status values and skills to Kumoko when they return. So Kumoko gets a huge power-up to save the day and Mother is killed pretty easily. This completely breaks the Kin Domination link. However, one of the Parallel Wills is missing - one had gone to attack Ariel and doesn't return.

So while Kumoko eventually gets some skills/status from Mother like in the WN, it’s a lot more work. In addition, the Kin Domination link is completely gone so Kumoko herself can’t attack Ariel or the other Queens. Kumoko also doesn’t get Mother’s memories and will later have to learn the language the hard way.

So in the end Kumoko leaves the labyrinth again, but since Ariel is out there she wants to keep a low profile. This is when she comes across Sophia for the first time, like in the WN.

---- for the side stories:

On Shun's side, there's not many changes - there's some smaller changes because Fey is around.

Fey transforms to human right at the start - before they enter the Labyrinth (it seems she could do this as soon as she became a Light Earth Drake). Unsurprisingly, given the previous cases of Shiro and Wrath, her humanoid form has her face from the previous world - which she is quite happy about since she was always confident about her looks. It's not a perfect transformation to human though - she still has some vestiges of being a dragon, though her stubby white her wings etc make her look like an angel instead. One interesting thing - her weight is still the same as when she was a dragon (though gravity manipulation magic is being used to mitigate it). This is why Shun gets into that scene shown on one of the images - Fey can't swim well and because of her weight only Shun is strong enough to be able to carry her...

The short scene where Shun sees Sariel while asleep is the same as in the WN. The next night, Shun has another "significant dream" - a more vague one where he sees when Julius's hero party fought one of the Remnants of the Nightmare. He sees the outline of a girl in while.

There's even a third dream where he remembers walking into class and towards his friends, noticing various people. He notices a spider’s nest near Kyouya and Kanata, then when he looks forwards again Rihoko is standing in front of him while glaring and reaches out towards him.... (and then he wakes up). He notes that he's been having many odd dreams since he came to the Labyrinth. He only had these odd dreams while in the Labyrinth though (they stop after he leaves).

Just before they reach the elf village. Katia tells Shun about the dead reincarnators. It's pretty much the same except Shun thinks to himself about how Katia (or rather Kanata in the previous life) confessed to Wakaba.

One more general change is that Shun is much more aware that there's others (Ronant and Sophia in particular) who are much stronger than him. So compared to the WN he's more melancholy about his lack of strength and not quite so quick to take risks.

Once they get to the village, the main difference is that future events are foreshadowed more, particularly around Kyouya - in the WNs, Kyouya's situation is pretty much a complete mystery until he arrives and ditto why he has his old face. In the LN, Fey's situation foreshadows Kyouya (and "Wabaka" or rather Shiro) and also, because Sophia is revealed much earlier, that is also used to hint (to Shun) about Kyouya. They find out from Oka-chan sensei that Sophia = Negishi Akiko and that she's probably serving an Administrator, but oddly there's no discussion about her being Rihiko so a LN only reader might think that Rihoko = MC and that Rihoko is someone other than Sophia.

Anyway, Shun guesses based on Oka-chan's evasiveness that Kyouya might also be serving under an Administrator and he wonders what happened to Kyouya. The very next chapter is a discussion between Kyouya and Sophia. Although Kyouya's name doesn't come up, it's quite heavily hinted that this is in fact Kyouya - the chapter title is "the reincarnators who sided with the administrators" and the person talking with Sophia mentions looking forward to seeing Kanata and Shun. So, in the next LN, when we finally get to Sophia and Wrath showing up before Shun like in the WN, it'll be much less of a surprise. Sophia won't need to introduce herself really, though Shun might be surprised that she and Kyouya are with the demons.