It is... well the future, a time when all teenagers muscle and fat mass render each individual gender indistinguishable from the outside. Not to mention they seem to only have bones for their arms and legs. This may in fact have something to do with the random disappearance of elements in the world.

Yes randomly out of no where elements, off the periodic table, are just up and vanishing. When this happens great disaster follows. However, some how in the future we have figured out that all of the elements we have discovered have gone to another dimension, to a Nega Earth.

It is up to a few chosen children, with special gifts to go to the Nega Earth, with the mission of getting the elements back. They are trained and clad in extra tight clothing so as to make killing the monsters who have consumed these disappearing elements seem more bad ass than it actually is. All for the sake of keeping earth from ceasing to exist.