He is the main protagonist who goes by the name Nezumi Kozo at night when he fights against the injustices done against the town's people, by day he is known as Mr. Helper who does a myriad of very unusual and odd jobs. He's not very good with money since he will squander all his pay in gambling at the end of the day, which is why his sister Koharu doesn't trust him to run her decorative chopstick shop for fear that he may use the shop's earnings to finance his gambling habit.

He has a fascination with Okuni Taiyu a well known courtesan in Shimabara.