Sure, half for you half to get myself straight.
So after the party descended to layer 6 they go about the usual exploring business. One night Faputa sneaks in, steals the Prushka Stone to bring to the village to bring out its true form (After the Bondrewd arc Prushka's heart became the Life Worth Stone they needed to descend out of her desire to adventure with Riko), left a "test" for Reg in the form of the picture with the "Haku" mark to see if he remembered her/was actually Reg, and created wards so the party wouldn't be attacked. She did all this to guide Reg to the village so he would remember his promise to her.
Flashback to that promise. On the way to the surface (Likely on Lyza's orders) Reg meets Faputa and learns her side of things. They bond and he promises to help her achieve her goal (getting revenge for her mother) once her goes to the surface and finds his "Haku" (Riko). Faputa was born out of rage towards what the villagers did to her mother and is a being of revenge.
Flashback even further to the village's creation. The Ganja Corps, a group of exiles searching for a promised homeland, are led to the Abyss by the Star Compass. On the way down they end up "adopting" Irumyui, one of the local tribeswomen exiled for being infertile. Vueko (One of the 3 sages and the woman talking to Wazukyan this chapter) gets especially close to her. They eventually make it to layer 6 (Unknown what layer it was at the time as the Abyss has been implied to slowly grow deeper every 2,000 or so years) and find the Golden City of legend! Too bad it's a hellscape and not a promised land, but the group decides to make it their own and gets to work. Unfortunately the Abyss kinda sucks and everyone gets sick. To save everyone as a last ditch effort Wazukyan (Currently the Narahate with the black face and tendrils), one of the "three sages" of the group, gives Irumyui a Cradle of Greed that supposedly grants wishes but can only be used by children. He was hoping her wish would be to live and would end up saving them, but her wish ends up being to be able to give birth (remember she was exiled for being infertile and her society seemed to place great importance on motherhood). The "babies" die as soon as they are born, but it turns out that eating them cures the group and sustains them. Over time Irumyui grows more and more monstrous and has a 2nd cradle put into her by Wazukyan, this one likely holding a wish to give them a safe haven or homeland of some kind. Around this time Wazukyan also uses a Cradle on himself to try to help the party, though its unknown what it does. It might have done nothing because he wasn't a child, or it might be the reason them eating Irumyui's kids cured them.
Long story short: Irumyui becomes the village, the Ganja Corps give themselves up to her and become Narahate, she absorbs the 3 Cradles and gives birth to her only surviving child Faputa, and Vueko gets imprisoned.
Flash forward. The main party goes to the village, meets people, helps in a hunt, finds the Prushka stone being made into a white whistle etc. Nanachi ends ups selling herself to the last of the 3 sages Belaf (Snake man) to save Mitty! But it's not actually Mitty. It's a replicant created by the village after Belaf saw Mitty on one of Bondrewds delves to the 6th layer. (He apparently came down her quite a bit and could survive the ascent due to the cartridges).
Rico ends up free Vueko from her imprisonment and learns the history of the village from her. She also enda up connecting with some of the villagers and learns they were all explorers like herself at one point.
Reg (having lost his memories) meets with Faputa and learns he was somehow named Reg on the way up before Rico gave him that name. He also learns he used to know Faputa and they were close. Turns out Faputa knows his past and he's very curious but also very uneasy.
In exchange for helping her with the "promise" he made to her, Reg gets part of Faputa's body to exchange for Nanachi back. However when he enters the village it recognizes it as a piece of it's daughter and all hell breaks loose. Faputa then arrives and when it comes time to pay his debt and help Faputa exterminate the village he backs out and says he wants to protect the village that he and Rico have gotten to know.
Fight ensues, Reg loses, this chapter happens. Apparently Wazukyan basically never wanted this village but wants to keep exploring layer 6, the village was basically an emergency button he made to survive layer 6. He's been waiting for a child who can use a cradle to come down here and plans to get Rico to use one of the 3 Cradlea Faputa inherited to achieve that goal. Currently the villagers are stuck within the village as leaving kills them.
Belaf ends up relaying his memories to Nanachi and letting her go after remembering his past when Faputa showed up. He then, in this chapter, died fighting Faputa and gave her his memories too. Now knowing that the villagers aren't evil monsters, but aren't guiltless in turning her mother into the village wither, Faputa is at a crossroads.
Party goals atm are to basically survive and calm Faputa down, which after getting context she kinda has, and to not let Wazukyan use Rico. The village is falling apart though from the Faputa/Reg fight and Abyss monsters are getting in now.