This is probably my favorite genre-savvy take on the "hero" and "isekai" trends in light novels - in this series, a so-called goddess gets into the minds of dying children and turns them into "heroes" by letting them think they're living in their dream world, but they're actually causing massive death and destruction in reality. Only people under the age of twenty can see the heroes, and so it's up to them to stop them. It's cruel but in a way that doesn't feel excessive, and even as I recognized its schlocky elements, I had a hard time putting it down.