>>3542694That's the great thing about Tsukushi's work, a lot of the details are in the scenery, less infodump and more storytelling through visuals and reasoning. Delvers showing up in the 4th layer are mostly just black whistles and sometimes moon whistles accompanied by black whistles. Nanachi didn't take chances with delvers and only brought back the solo ones to her hut that she believed couldn't kill her. In that case it was almost always those who were envenomed by Tama-chan. Think about how many graves were in the back yard, and how they all were covered in moss. Also consider Prushka's upbringing and how she was carefully reared to have a strong bond for Bondrewd. He learned how that was important for being blessed by the abyss from Nanachi and Mitty. There's a slight time dilation between the 4th and 5th layers, but not a whole lot of difference. If you really consider everything shown to you, it's easy to conclude that there were at least a couple years between when Nanachi made it to the 4th layer, and when Riko and Reg arrived. Not to mention the ascent from the 5th to the 4th layer probably took a long time and careful movements upward.
