Manga no Matsuri

The power of the Konkuris is immensely powerful and they can easily lose control. That's why the Hotekis, "enlightened" people responsible of balance, keep them under control using their cursed powers to open stargates to ultra-terrestrial worlds in a program called "Isekaiki", where the empowered humans Shujins are sent to conquer them. The more achievement the Shujins of a Konkuri get, the Higher ranked the Konkuri is. And every 3 months, the last Konkuri in the ranking is sealed.