Mao Asou

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.

Eiko Yagami is a "Marubo", a unit of Ueno Central Police Station's Organized Crime Division which deals directly with organized gangs to try and keep the peace. However, Eiko has some sidelines: she's a moneylender to her fellow police officers without charging interest in return for information and is also willing to do the odd side job for those on the criminal side for the money. One day, Kasumi, who is the daughter of Senma-gumi gang's leader, is found stabbed to death. As this threatens to pit gang against gang, Eiko and the police have to hurry and find her killer.