From MangaHelpers:

The Japanese National Diet building has somehow been scooped out of the earth, with all the congressmen inside. They don't know where they are, but they still have power and internet, and a small opening to get food and supplies from Earth. Therefore, their needs are taken care of, but they are trapped completely.

Among the congressmen, there are a group of 20-something men who are not generally respected as politicians. These are congressmen who were chosen to improve the image of their parties. Among them are former idols and entertainers (Makise Jin, Yoshizawa Rei), a former comedian (Himei Shougo), a former Olympic figure skater (Ichinose Daiki), an ordinary office worker (Momosawa Kenta), and one young man who really has a passion for politics (Uesugi Ryou). Three weeks into their confinement, they happen upon a young girl who has mysteriously appeared in the building. She remembers nothing of herself, except that her name is Itagaki Taisuke, which is actually the name of a famous historical Japanese politician. Could she really be Itagaki Taisuke reborn, come to help them become better congressmen? [tethysdust]