How 23 Students Saved the Galaxy

Almost a year has passed since the so-called Korean Terrorist Attacks of 2020, as dubbed by many countries, and that means a new school year for the students who practically saved the world at the now-known NCT school in South Korea. As they, along with a couple of new students as well, try to start a new year of high school in peace, it soon becomes clear that there is something wrong going on again in their little school - and not only do they got to fight these aliens, but they might need to leave the planet as well once knowing that the whole Milky Way could collapse. They saved the world, sure, but... can they do it again?