The fourth episode of Made in Abyss, entitled the Edge of the Abyss, sees Reg and Riko begin there travel down into the depths of the abyss. Reg uses his arms to great effect in this episode showing his versatility and usefulness in traversing the abyss. Riko has her usefulness as well, she has general known of the surrounding flora and fauna, as well as cooking. Reg gives Riko an envelope featuring a replica of her mother’s sealed letter.
Reg speculates that the letter was placed in his pocket by Leader, Riko reads a note stating that leader will pursue them at dawn. Reg and Riko conclude that this is a test to see if they are worthy of begin explorers. They encounter a strange spider like creature called Silkfangs, that is limited in movement by webs. The episode fails to explain what the creature is and why it’s limited by web. I think this was a missed opportunity to further reveal the world.
Reg notices a green light in the distance and conclude that it must be a search party. It turns out that their pursuer is Black Whistle Hablog and he wants to see the “supreme treasure of the netherworld,” he like Riko in a previous check the “balls,” of Reg. Regardless, he explains that Nat and Shiggy hired him to help them get to the second layer. Riko tells him while she appreciates his help the mission is their “last test.” Hablog accepts this and gives Riko a vaccine for the second layer, mustard steamed and a warning regarding “Ozen the Immovable.” However, Riko doesn’t appear to consider the warning that serious, she and Reg finally arrive in the second layer, the Forest of Temptation.