Arknights: Unbreakable Wall

Warning: I do not own the characters besides my own creation and the picture used for the book is not mine. What would happen if someone with no will to fight is thrown into a dying world filled with violence, death, and infection? What would someone do if he realizes that the world could end at any moment? He will become an wall that everyone leans on, a wall that everyone depends on. An Unbreakable Wall.