Puppet Mama and Spider Boy were only a warm-up for two of the three remaining members of the Spider Demon Family: Father and Rui. Needless to say they are much tougher customers, which is as it should be; why would the difficulty level go down in a demon gauntlet?
Even with Water Breathing, Tanjirou isn’t able to slice through one of Papa’s arms, and Inosuke inarguably saves his life by parrying the counterattack. Even dropping a huge tree on Papa doesn’t kill him, it only seems to make him mad. As Tanjirou goes flying, he begs Inosuke not to die, but wait for him to make his way back to him.
Zenitsu defeated Spider Boy definitively, but continues to pay the price as the poison starts shutting down his limbs. He’s all but ready to step into the light when a series of butterflies appear before him, followed by Shinobu, one of the two elite Demon Slayers sent to salvage the mission.
Tanjirou manages to cushion his fall with water breathing, but he’s only thrown from the frying pan to the freezer. Due to his strong sense of family and morality, he objects to the Spider Brother Rui apparently punishing his sister by cutting her face with his threads as she cries out in pain. Demon or no, that’s not cool. The Brother doesn’t take well to being told his familial bond with his sister is nothing but a sham.
Rui threatens to carve Tanjirou up, but is momentarily distracted by another Demon Slayer who comes out of nowhere. While claiming to be taking the easiest path to higher ranks (and higher paydays), he doesn’t practice what he preaches. He rushes in without knowing a thing about Rui, who dices him into cubic chunks with his threads.
Finally, we have Inosuke, trying to hold out against Papa Spider. While he briefly starts “using his head” like Tanjirou, he shakes that off and follows his own primal instinct to charge the enemy without fear. He keeps hacking at the arm until he manages to slice through, and Papa flees…but only to molt his own skin, revealing a bigger, tougher, meaner skin beneath it.
Inosuke’s chipped blades shatter when he attempts Beast Breathing, and Papa grabs him by the head and squeezes. Inosuke’s life flashes before his eyes, including when his bloodied mother sent him away to avoid being killed, and the interactions with Tanjirou and Zenitsu which seems to value.
Just before his skull pops (and the foley is pretty ripe) Inosuke is rescued by Giyuu, who cuts off Papa’s arm with one slash and defeats him with a single elegant Water Breathing Form. It’s a pretty convincing and awesome demonstration of just how much more powerful Giyuu is than Tanjirou, Zenitsu, or Inosuke.
Inosuke is safe, and so too is Zenitsu, but Tanjirou is still out there on his own against Rui, and we get a cliffhanger of Rui’s vicious thread cutting straight through Tanjirou’s sword on a collision course with his face. It’s a big forest, so it could take a while for help to arrive. Could the sister demon be an unlikely ally to Tanjirou? And what about his own sister—when will she pop out of her box?