From: ANN

The action story is set in Edo-era Tokyo in the early 1700s. The eighth shogun Tokugawa Yoshimune ordered boxes to be installed so commoners can submit their thoughts. After hearing their voices, the shogun creates a new magistrate unit — Mushibugyou — to protect the people in the heart of the city. Each member is a specialist with unique fighting skills.

The story takes place in Ikebukuro, Tokyo. The main character, Yamato, cares a lot about his younger twin brother, Yuuto, and is unable to confess to Michiru, his childhood friend. One day those three are shocked by a sudden situation... !!!

The people have demanded change, Criterion boxes were created for the purpose of the people to leave their complaints in it. The result of this were two changes: the first being the creation of of 'Koishigawa Youjoujo' for the people, the second being an inner-city magistrate office, known as the Mushibugyo.

Tsukishima Jinbee is a warrior who aims to be best, under the belief that a weak warrior isn't a warrior at all. He was scouted out by a representative to join the Mushibugyo and told to go to Edo with the instructions that he'd knew what to do once he got there. Shortly after arriving at Edo, he hears a scream and goes to check it out... To find a giant spider-like creature devouring some citizens of Edo. Being a warrior, there's no way he could stand this...