Chapter five of Black Paradox.
Marusou has a premonition of something dreadful happening. Suka pays a homeless man to dive inside the giant stomach that came from Piitan and enter through the spirit door; but it fails as the man's body disintegrates into goo. Suka wants to explore the spirit world in order to solve Japan's future problems of lack of resources, but all cameras and surveillance equipment he has sent inside it have been destroyed.
Baracchi suggests they use the Piitan robot. It is still full of power from the spirit energy. It joyfully agrees to go inside the stomach as a method of suicide but, contrary to Suka's expectations, it survives the trip. It says this happened because it is Piitan and the stomach is Piitan's. The robot begins to produce the jewels, but when asked about the spirit world can only say that it saw a beautiful, dazzling world.
Suka seduces Baracchi and Taburou, seeing no reason to stay, decides to get out of there. He ponders freeing Marusou, but leaves her there when he finds her in a terrified fit and she screams that bad things will happen to all of them. He returns home to the mansion he bought but is confronted by his doppelganger. Suka shows Baracchi a separate portal that he cultivated from her birthmark. The robot refused to enter this portal as it came from Baracchi's, so told Suka to speak to Baracchi herself.
Suka invites government ministers and other important people to witness first the Piitan robot diving inside the stomach to collect Paradoxical Night jewels, then Baracchi entering her own portal. At first she appears to emerge unharmed, but then her skin starts to melt away, rapidly revealing that she was a robot too.