Satomi Ishihara

When a massive, gilled monster emerges from the deep and tears through the city, the government scrambles to save its citizens. A rag-tag team of volunteers cuts through a web of red tape to uncover the monster's weakness and its mysterious ties to a foreign superpower. But time is not on their side - the greatest catastrophe to ever befall the world is about to evolve right before their very eyes.

100 years ago, titans suddenly appeared on Earth. Soon, human civilization veered on collapse due to the titans. Humans then built a giant wall to defend themselves. Within the giant walls, humans lived in peace, but, 100 years later, the giant wall is broken.