The 10th Hierarchical City "Akitsu-Otsu" (第十階層都市「アキツ―乙」 Dai-Jū Kaisō Toshi "Akitsu-Otsu") is a city in the Ikaruga Federation. It is situated in Russia.
The 9th Hierarchical City "Akitsu-Kō" is located right beside this city, the two together from a pair and are simply referred to as Akitsu. They form one of the tree pairs of the twin Hierarchical Cities. Akitsu-Kō's broken environment maintenance device is influencing Akitsu-Otsu, but while the ninth city is covered in snow, the tenth city contains a desert.
- The 9th Hierarchical City "Akitsu-Kō" and 10th Hierarchical City "Akitsu-Otsu" are named after the Japanese god and goddess Hayaakitsuhiko no kami and Hayaakitsuhime no kami.