MODERN WORLD X ISEKAI WORLD

One day, suddenly in all major countries, a strange large door appeared that connected to another world, one of which was in Japan, people named the door with the word GATE where if the world was entered, the person who entered would be teleported to that world, but because GATE was still considered strange and had not been investigated, all GATEs in all countries and the world were still tightly guarded by the military, but on October 28, 2026, GATE overflowed and from inside there appeared a group of troops from that world who attacked all countries, but all the troops were easy to fight because of the difference in technology and because of that situation the UN chairman ordered all presidents from all countries to immediately carry out an expedition to that other world with the military power of each country