Comprehensive Comic: Survival at the End of the World

[Girls Frontline+Azur Lane+Battleship Girls+Red Alert+Rust War+? (If you want to add anything else, you can tell yourself.)] The protagonist traveled to the parallel world of Earth in 2012. He originally thought it was just a normal world, but when he looked at the hole in the sky, he fell into deep thought. I thought it was the world of a super seminary, but what about this monster, the armored warrior, the blood cross and the madly infected person? The most outrageous thing is not this. I can actually see recruitment advertisements for defenders. This world is unbearable at all.