After her werewolf lover unexpectedly dies in an accident, a woman must find a way to raise the son and daughter that she had with him. However, their inheritance of their father's traits prove to be a challenge for her.
Kyuta, a boy living in Shibuya, and Kumatetsu, a lonesome beast from Jutengai, an imaginary world. One day, Kyuta forays into the imaginary world and, as he's looking for his way back, meets Kumatetsu who becomes his spirit guide. That encounter leads them to many adventures.
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.
