Pictured: The submarine
A nuclear submarine found by Chito and Yuuri in episode 12 (manga chapter 27, volume 4). Entry was gained with the help of Nuko. The submarine was the site of both the meetings between the Eringi and the main cast and the departure of Nuko with his own kind. The girls departed from the submarine without Nuko, but with some canned soup and the new knowledge that their city's functions will eventually come to a halt.