I Don't Want to Play the World-Saving Game with the Chuunibyou Young Lady

A demon from the abyss went to great lengths to sneak into this world, hoping to return it to the abyss. But it met a grisly end in the street, simply because it ate food cooked with gutter oil.

After waiting ten thousand years, he finally became a god. When the deity descended upon Earth, he eagerly recruited followers, only to flee back to his divine realm badly wounded, simply because... he had lingered in a corner where a dog had peed and was mistaken for a rival fighting the dog for its territory.

After a thousand years of scheming, a mage from another world finally opened a passage to Earth. A million troops stood ready for battle, but they fled in disarray, and the entire world was contaminated by a black slime, simply because they had opened the passage in a city sewer on Earth…